DZS INC. - Annual Report: 2012 (Form 10-K)

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2012

OR

For the transition period from                      to                     

Commission File Number: 000-32743

ZHONE TECHNOLOGIES, INC.

(Exact name of registrant as specified in its charter)

7195 Oakport Street

Oakland, California 94621

(Address of principal executive office)

Registrant’s telephone number, including area code: (510) 777-7000

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ¨    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act.    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Exchange Act during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be filed to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definitions of “accelerated filer,” “large accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  x

As of March 1, 2013, there were 31,120, 165 shares outstanding of the registrant’s common stock, $0.001 par value. As of June 29, 2012 (the last business day of the registrant’s most recently completed second fiscal quarter), the aggregate market value of common stock held by non-affiliates of the registrant was approximately $16,272,124.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive Proxy Statement for the 2013 Annual Meeting of Stockholders are incorporated by reference into Part III of this Form 10-K where indicated.

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Forward-looking Statements

This Annual Report on Form 10-K, including “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” contains forward-looking statements regarding future events and our future results that are subject to the safe harbors created under the Securities Act of 1933 and the Securities Exchange Act of 1934. These statements are based on current expectations, estimates, forecasts, and projections about the industries in which we operate and the beliefs and assumptions of our management. We use words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “goal,” “intend,” “may,” “plan,” “project,” “seek,” “should,” “target,” “will,” “would,” variations of such words, and similar expressions to identify forward-looking statements. In addition, statements that refer to projections of earnings, revenue, costs or other financial items; anticipated growth and trends in our business or key markets; future growth and revenues from our Single Line Multi-Service, or SLMS, products; our ability to refinance or repay our existing indebtedness prior to the applicable maturity date; future economic conditions and performance; anticipated performance of products or services; plans, objectives and strategies for future operations; and other characterizations of future events or circumstances, are forward-looking statements. Readers are cautioned that these forward-looking statements are only predictions and are subject to risks, uncertainties and assumptions that are difficult to predict, including those identified under the heading “Risk Factors” in Item 1A, elsewhere in this report and our other filings with the Securities and Exchange Commission (the SEC). Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. Factors that might cause such a difference include, but are not limited to, the ability to generate sufficient revenue to achieve or sustain profitability, the ability to raise additional capital to fund existing and future operations or to refinance or repay our existing indebtedness, defects or other performance problems in our products, the economic slowdown in the telecommunications industry that has restricted the ability of our customers to purchase our products, commercial acceptance of our SLMS products, intense competition in the communications equipment market from large equipment companies as well as private companies with products that address the same networks needs as our products, higher than anticipated expenses that we may incur, and other factors identified elsewhere in this report. We undertake no obligation to revise or update any forward-looking statements for any reason.

PART I

Company Overview

We design, develop and manufacture communications network equipment for telecommunications, wireless and cable operators worldwide. We believe that these network service providers can increase their revenues and lower their operating costs by using our products to deliver high quality video and interactive entertainment and Internet Protocol (IP) enabled next generation voice services in addition to their existing voice and data service offerings, all on a platform that permits a seamless migration from legacy technologies to a converged packet-based architecture. Our mature SLMS architecture provides cost-efficiency and feature flexibility with support for voice over internet protocol (VoIP) and IP entertainment (IPTV). Within this versatile SLMS architecture, our products allow service providers to deliver all of these and other next generation converged packet services over their existing copper lines while providing support for fiber or Fiber to the home or business (FTTx) build-out. With our products and solutions, network service providers can seamlessly migrate from traditional circuit-based networks to packet-based networks and from copper-based access lines to fiber-based access lines without abandoning the investments they have made in their existing infrastructures.

In addition to our established product offerings, Zhone launched our flagship MXK IP Multi-service Terabit Access Concentrator (MXK) and multiple new Optical Line Terminal (OLT) and outdoor units in late 2009. Our MXK product is a converged multi-services access platform that can be configured as a Gigabit Passive Optical Network (GPON) or Active Ethernet OLT. The MXK GPON line module is ITU-T G.984 compliant, delivering data throughputs of up to 2.5 Gbps downstream and 1.25 Gbps upstream. Each line card is designed for up to 64 passive splits per fiber. Active Ethernet delivers up to 100 Mbps point-to-point from a 20-port card. In 2012, we shipped more than 2,200 MXK systems to new and existing customers globally. MXK continues to be widely

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deployed by service providers around the world, with more than 4,400 total MXK units now deployed at over 150 service providers in more than 40 countries. Also in 2012, Zhone launched our new FiberLAN Optical LAN solution (OLS). We believe FiberLAN OLS is one of the most cost-effective, efficient and environmentally friendly alternatives to existing copper based Ethernet LAN infrastructure. Our FiberLAN OLS is comprised of our MXK OLT and zNID ONT, and delivers GPON-based LAN services to enterprises.

Zhone’s MXK product supports the next generation of high-performance business and residential FTTx services. Unlike most competing products, MXK has the ability to support both Passive Optical Network (PON) and Active Ethernet fiber technologies to the node, curb or premises. With our MXK product, service providers can offer digital or Ratio Frequency (RF) video, high-bandwidth Internet access, VoIP and cell relay services from a single OLT over IP. Additionally, our MXK product provides Zhone with industry leading density featuring an 8 port GPON Module enabling support for up to 9,216 GPON subscribers in a single MXK chassis.

The flexibility of our MXK product enables service providers to choose the best technology for both services and network architecture. Active Ethernet provides dedicated high symmetric bandwidth to the end customers and makes it an excellent technology for deployment of business services. GPON provides a cost-effective way to deliver high bandwidth to the residence for a robust triple play offering while enabling a host of high speed data and video options for the businesses. In addition to Active Ethernet and dense GPON support, the MXK provides a wide array of multi-service functionality supporting well defined access standards enabling the convergence of voice, data and entertainment over any access medium delivering high-performance all IP solutions designed for today’s traffic mix.

Corporate Information

We were incorporated in Delaware under the name Zhone Technologies, Inc. in June 1999, and in November 2003, we consummated our merger with Tellium, Inc. (Tellium). Although Tellium acted as the legal acquirer, due to various factors, including the relative voting rights, board control and senior management composition of the combined company, Zhone was treated as the “acquirer” for accounting purposes. Following the merger, the combined company was renamed Zhone Technologies, Inc. and retained substantially all of Zhone’s previous management and operating structure. The mailing address of our worldwide headquarters is 7195 Oakport Street, Oakland, California 94621, and our telephone number at that location is (510) 777-7000. Our website address is www.zhone.com. The information on our website does not constitute part of this report. Through a link on the Investor Relations section of our website, we make available the following filings as soon as reasonably practicable after they are electronically filed with or furnished to the SEC: our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and any amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934. All such filings are available free of charge.

Industry Background

Over the past decade, the communications network industry has experienced rapid expansion as the internet and the proliferation of bandwidth intensive applications and services have led to an increased demand for high bandwidth communications networks. The broad adoption of new technologies such as smartphones, digital cameras and high definition televisions allow music, pictures, user-generated content (as found on the many video-sharing sites) and high definition video to be a growing part of consumers’ regular exchange of information. In recent years, the growth of social communications and social networking has continued to place demands on existing copper based access infrastructure and new consumer demands are challenging even the newest and most advanced infrastructures. All of these new technologies share a common dependency on high bandwidth communication networks and sophisticated traffic management tools. However, network service providers have struggled to meet the increased demand for high speed broadband access due to the constraints of the existing communications network infrastructure. This infrastructure consists of two interconnected networks:

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To address the increased demand for higher transmission speeds via greater bandwidth, service providers have expended significant capital over the past decade to upgrade the core network by replacing much of their copper infrastructure with high-speed optical infrastructure. While the use of fiber optic equipment in the core network has relieved the bandwidth capacity constraints in the core network between service providers, the access network continues to be a “bottleneck” that severely limits the transmission speed between service providers and end-users. As a result, communications in the core network can travel at up to 10 gigabits per second, while in stark contrast, many communications over the access network throughout the world still occur at a mere 56 kilobits per second, a speed that is 175,000 times slower. At 56 kilobits per second, it may take several minutes to access even a modestly media laden website and several hours to download large files. Fiber access lines have the potential to remedy this disparity, but re-wiring every home or business with fiber optic cable is both cost prohibitive and extremely time consuming. Consequently, solving the access network bottleneck has typically required more efficient use of the existing copper wire infrastructure and support for the gradual migration from copper to fiber.

In an attempt to deliver high bandwidth services over existing copper wire in the access network, service providers began deploying digital subscriber line (DSL) technology over a decade ago. However, this early DSL technology has practical limitations. Copper is a distance sensitive medium in that the amount of bandwidth available over a copper wire is inversely proportional to the length of the copper wire. In other words, the greater the distance between the service provider’s equipment and the customer’s premises, the lower the bandwidth. Unfortunately, most DSL services available today are provided by first generation DSL access multiplexer (DSLAM) equipment. These large unwieldy devices require conditioned power and a climate controlled environment typically found only in a telephone company’s central office, which is often at great distance from the customer. While adequate for basic data services, these first generation DSLAMs were not designed to meet the needs of today’s high bandwidth applications. The modest bandwidth provided by existing DSLAM equipment is often incapable of delivering even a single channel of standard definition video, much less multiple channels of standard definition video or high definition video.

Over the past decade, regulatory changes have introduced new competitors in the telecommunication services industry. Cable operators, with extensive networks designed originally to provide only video programming, have collaborated to adopt new packet technologies that leverage their hybrid fiber/coaxial cable infrastructure. Using more recent technologies, cable operators have begun to cost-effectively deliver new service bundles. The new service offerings provide not only enhanced features and capabilities, but also allow the cable operators to deliver these services over a common network. The resulting cost-efficiencies realized by cable operators are difficult for incumbent telephone companies to match. Even with the telephone companies’ legacy voice switches fully paid for, maintaining separate networks for their circuit-based voice and packet-based video and data networks is operationally non-competitive. Perhaps even more important than economic efficiencies, by integrating these services over a common packet infrastructure, cable operators will realize levels of integration between applications and new features that will be difficult to achieve from a multi-platform solution. Despite these benefits, coaxial cable has its own share of limitations. Unlike DSL, coaxial cable shares its bandwidth among all customers connected to it. Consequently, as new customers are added to coaxial cable networks, performance decreases. As a shared medium, large numbers of subscribers who simultaneously access the same segment of the coaxial cable network can potentially compromise performance and security. This represents a source of strategic advantage for telecom operators who employ technology designed to maximize their service capabilities on the point-to-point (i.e. not shared) architecture of their copper infrastructure. In addition, the introduction of 3G and 4G wireless technologies and improved satellite technologies have enabled wireless and satellite service providers to provide competitive broadband offerings as alternatives to traditional landline access. This increased competition has placed significant pressure on all network service providers. With significant service revenues at risk, these service providers have sought to upgrade and modernize their networks and broaden their service offerings to enable delivery of additional high bandwidth, high margin services, and to lower the cost of delivering these services.

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The Zhone Solution

We believe that we are the first company dedicated solely to developing the full spectrum of next-generation access network solutions to cost-effectively deliver high bandwidth services while simultaneously preserving the investment in legacy networks. Our next-generation solutions are based upon our SLMS architecture. From its inception, this SLMS architecture was specifically designed for the delivery of multiple classes of subscriber services (such as voice, data and video distribution), rather than being based on a particular protocol or media. In other words, our SLMS products are built to support the migration from legacy circuit to packet technologies and from copper to fiber technologies. This flexibility and versatility allows our products to adapt to future technologies while allowing service providers to focus on the delivery of additional high bandwidth services. Because this SLMS architecture is designed to interoperate with existing legacy equipment, service providers can leverage their existing networks to deliver a combination of voice, data and video services today, while they migrate, either simultaneously or at a future date, from legacy equipment to next-generation equipment with minimal interruption. We believe that our SLMS solution provides an evolutionary path for service providers using their existing infrastructures, as well as giving newer service providers the capability to deploy cost-effective, multi-service networks that can support voice, data and video.

Triple Play Services with Converged Voice, Data and Video – SLMS simplifies the access network by consolidating new and existing services onto a single line. This convergence of services and networks simplifies provisioning and operations, ensures quality of service and reliability, and reduces the time required to provide services. SLMS integrates access, transport, customer premises equipment, and management functions in a standards-based system that provides scalability, interoperability and functionality for voice, data and video services.

Packet Migration – SLMS is a flexible multi-service architecture that provides current services while simultaneously supporting migration to a pure packet network. This flexibility allows service providers to cost-effectively provide carrier class performance, and functionality for current and future services without interrupting existing services or abandoning existing subscribers. SLMS also protects the value of the investments made by residential and commercial subscribers in equipment, inside wiring and applications, thereby minimizing transition impact and subscriber attrition.

Fiber to the Home, Premise, Node, or Curb (FTTx) – We provide support for the full range of fiber-based access network architectures that are seeing increased use by carriers. In many markets worldwide, both business and residential demand for bandwidth is growing to the point where the deployment of fiber in the access network is increasingly desirable. Where copper loops are plentiful and where civil restrictions make fiber deployment all the way to the customer premises prohibitively expensive, if not impossible, many operators are choosing to deploy fiber from central offices to neighborhoods and then using VDSL2 over copper to deliver broadband connectivity over the last hundred meters or so. In other circumstances operators choose to deploy passive optical networks (PON) all the way to the customer premises, where a single fiber’s bandwidth is shared through splitters with up to 64 subscribers. Some circumstances demand so-called “home run” fiber networks (with dedicated fiber resources linking every customer directly to the central office) to maximize bandwidth or service segmentation. By supporting all these architectures within a common SLMS-based platform, we provide carriers maximum flexibility to build the network that best suits their needs.

Ethernet Service Delivery – We offer a complete array of equipment that allows carriers to deliver ethernet services over copper or fiber. For business subscribers, our ethernet over copper product family allows carriers to quickly deliver ethernet services over existing copper SHDSL or T1/E1 circuits. Multiple circuits can be bonded to provide over 70 Megabits per second, enough to deliver ample ethernet bandwidth to satisfy business subscribers’ growing service requirements. This copper-based solution provides a compelling alternative to burying fiber and dedicating valuable fiber strands to long-haul ethernet services to small and medium enterprises.

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The Zhone Strategy

Our strategy has been to combine internal development with acquisitions of established access equipment vendors to achieve the critical mass required of telecommunications equipment providers. We expect that our future growth will focus primarily on organic growth in emerging technology markets. Going forward, the key elements of our strategy include:

Product Portfolio

Our products provide the framework around which we are designing and developing high speed communications software and equipment for the access network. All of the products listed below are currently available and being shipped to customers. Our products span two distinct categories:

SLMS Products

Our SLMS products address three areas of customer requirements. Our Broadband Aggregation and Service products aggregate, concentrate and optimize communications traffic from copper and fiber networks. These products are deployed in central offices, remote offices, points of presence, curbsides, data and co-location centers, and large enterprises. Our Customer Premise Equipment, or CPE, products offer a cost-effective solution for combining analog voice and data services to the subscriber’s premises over a single platform. The Zhone Management System, or ZMS, product provides optional software tools to help manage aggregation and customer premises network hardware. These products deliver voice, data and video interface connectivity for broadcast and subscription television, internet routers and traditional telephony equipment.

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Our SLMS products include:

Legacy, Service and Other Products

Our legacy products support a variety of voice and data services, and are broadly deployed by service providers worldwide. Our main legacy product during 2012 and 2011 was our IMACS product which functions as a multi-access multiplexer.

Global Service & Support

In addition to our product offerings, we provide a broad range of service offerings through our Global Service & Support organization. We supplement our standard and extended product warranties with programs that offer technical support, product repair, education services and enhanced support services. These services enable our customers to protect their network investments, manage their networks more efficiently and minimize downtime for mission-critical systems. Technical support services are designed to help ensure that our products operate efficiently, remain highly available, and benefit from recent software releases. Through our education services program, we offer in-depth training courses covering network design, installation, configuration, operation, trouble-shooting and maintenance. Our enhanced services offering is a comprehensive program that provides network engineering, configuration, integration, project management and other consultative support to maximize the results of our customers during the design, deployment and operational phases. As part of our commitment to ensure around-the-clock support, we maintain a technical assistance center and a staff of qualified network support engineers to provide customers with 24-hour service, seven days a week.

Technology

We believe that our future success is built upon our investment in the development of advanced technologies. SLMS is based on a number of technologies that provide sustainable advantages, including the following:

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Customers

We sell our products and services to network service providers that offer voice, data and video services to businesses, governments, utilities and residential consumers. Our global customer base includes regional, national and international telecommunications carriers. To date, our products are deployed by over 750 network service providers on six continents worldwide. Axtel S.A.B. DE C.V. (Axtel) accounted for 10% of net revenue in 2012 and 9% of net revenue in 2011. Emirates Telecommunications Corporation (Etisalat) accounted for 8% of net revenue in 2012 and 15% of net revenue in 2011. No other customer accounted for 10% or more of net revenue during either period.

Research and Development

The industry in which we compete is subject to rapid technological developments, evolving industry standards, changes in customer requirements, and continuing developments in communications service offerings. Our continuing ability to adapt to these changes, and to develop new and enhanced products, is a significant factor in maintaining or improving our competitive position and our prospects for growth. Therefore, we continue to make significant investments in product development.

We conduct the majority of our research and product development activities at our headquarters in Oakland, California. In Oakland, we have built an extensive communications laboratory with hundreds of access infrastructure products from multiple vendors that serve as an interoperability and test facility. This facility allows us to emulate a communications network with serving capacity equivalent to that supporting a city of 350,000 residents. We also have focused engineering staff and activities at additional development centers located in Alpharetta, Georgia; Largo, Florida; and Westlake Village, California.

Our product development activities focus on products to support both existing and emerging technologies in the segments of the communications industry that we consider viable revenue opportunities. We are actively engaged in continuing to refine our SLMS architecture, introducing new products under our SLMS architecture, and creating additional interfaces and protocols for both domestic and international markets.

We continue our commitment to invest in leading edge technology research and development. Our research and product development expenditures were $18.5 million, $21.4 million, and $21.2 million, in 2012, 2011 and 2010, respectively. All of our expenditures for research and product development costs, as well as stock-based compensation expense relating to research and product development, have been expensed as incurred. These amounts include stock-based compensation of $0.3 million, $0.2 million, and $0.4 million for 2012, 2011, and 2010, respectively. We plan to continue to support the development of new products and features, while seeking to carefully manage associated costs through expense controls.

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Intellectual Property

We seek to establish and maintain our proprietary rights in our technology and products through the use of patents, copyrights, trademarks and trade secret laws. We also seek to maintain our trade secrets and confidential information by nondisclosure policies and through the use of appropriate confidentiality agreements. We have obtained a number of patents and trademarks in the United States and in other countries. There can be no assurance, however, that these rights can be successfully enforced against competitive products in every jurisdiction. Although we believe the protection afforded by our patents, copyrights, trademarks and trade secrets has value, the rapidly changing technology in the networking industry and uncertainties in the legal process make our future success dependent primarily on the innovative skills, technological expertise, and management abilities of our employees rather than on the protection afforded by patent, copyright, trademark, and trade secret laws.

Many of our products are designed to include software or other intellectual property licensed from third parties. While it may be necessary in the future to seek or renew licenses relating to various aspects of our products, we believe, based upon past experience and standard industry practice, that such licenses generally could be obtained on commercially reasonable terms. Nonetheless, there can be no assurance that the necessary licenses would be available on acceptable terms, if at all. Our inability to obtain certain licenses or other rights or to obtain such licenses or rights on favorable terms, or the need to engage in litigation regarding these matters, could have a material adverse effect on our business, operating results and financial condition.

The communications industry is characterized by rapidly changing technology, a large number of patents, and frequent claims and related litigation regarding patent and other intellectual property rights. We cannot assure you that our patents and other proprietary rights will not be challenged, invalidated or circumvented, that others will not assert intellectual property rights to technologies that are relevant to us, or that our rights will give us a competitive advantage. In addition, the laws of some foreign countries may not protect our proprietary rights to the same extent as the laws of the United States.

Sales and Marketing

We have a sales presence in various domestic and foreign locations, and we sell our products and services both directly and indirectly through channel partners with support from our sales force. Channel partners include distributors, resellers, system integrators and service providers. These partners sell directly to end customers and often provide system installation, technical support, professional services and support services in addition to the network equipment sale. Our sales efforts are generally organized according to geographical regions:

Our marketing team works closely with our sales, research and product development organizations, and our customers by providing communications that keep the market current on our products and features. Marketing also identifies and sizes new target markets for our products, creates awareness of our company and products, generates contacts and leads within these targeted markets and performs outbound education and public relations.

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Backlog

Our backlog consists of purchase orders for products and services that we expect to ship or perform within the next year. At December 31, 2012, our backlog was $6.9 million, as compared to $7.3 million at December 31, 2011. We consider backlog to be an indicator, but not the sole predictor, of future sales because our customers may cancel or defer orders without penalty.

Competition

We compete in the communications equipment market, providing products and services for the delivery of voice, data and video services. This market is characterized by rapid change, converging technologies and a migration to solutions that offer superior advantages. These market factors represent both an opportunity and a competitive threat to us. We compete with numerous vendors, including Alcatel-Lucent, Calix, Adtran, Huawei, and ZTE, among others. In addition, a number of companies have introduced products that address the same network needs that our products address, both domestically and abroad. The overall number of our competitors may increase, and the identity and composition of competitors may change. As we continue to expand our sales globally, we may see new competition in different geographic regions. Barriers to entry are relatively low, and new ventures to create products that do or could compete with our products are regularly formed. Many of our competitors have greater financial, technical, sales and marketing resources than we do.

The principal competitive factors in the markets in which we presently compete and may compete in the future include:

While we believe that we compete successfully with respect to each of these factors, we expect to face intense competition in our market. In addition, the inherent nature of communications networking requires interoperability. As such, we must cooperate and at the same time compete with many companies.

Manufacturing

We manufacture our products using a strategic combination of procurement from qualified suppliers, in-house manufacturing at our facility in Florida, and the use of original design manufacturers (ODM) located in the Far East. Since our acquisition of Paradyne Networks, Inc., or Paradyne, in September 2005, we have been manufacturing a significant majority of our more complex products at our manufacturing facility in Florida.

Our parts and components are procured from a variety of qualified suppliers in the U.S., Far East, Mexico, and other countries around the world per our approved supplier list and detailed engineering specifications. Some completed products are procured to our specifications and shipped directly to our customers. We also acquire

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completed products from certain suppliers and configure and ship from our facility. Some of these purchases are significant. We purchase both standard off-the-shelf parts and components, which are generally available from more than one supplier, and single-source parts and components. We have generally been able to obtain adequate supplies to meet customer demand in a timely manner from our current vendors, or, when necessary, from alternate vendors. We believe that alternate vendors can be identified if current vendors are unable to fulfill our needs, or design changes can be made to employ alternate parts.

We design, specify, and monitor all of the tests that are required to meet our quality standards. Our manufacturing and test engineers work closely with our design engineers to ensure manufacturability and testability of our products, and to ensure that manufacturing and testing processes evolve as our technologies evolve. Our manufacturing engineers specify, build, or procure our test stations, establish quality standards and protocols, and develop comprehensive test procedures and processes to assure the reliability and quality of our products. Products that are procured complete or partially complete are inspected, tested, or audited for quality control.

Our manufacturing quality system is ISO-9001:2008 and is certified to ISO-9001:2008 by our external registrar. ISO-9001:2008 ensures our processes are documented, followed, and continuously improved. Internal audits are conducted on a regular schedule by our quality assurance personnel, and external audits are conducted by our external registrar every year. Our quality system is based upon our model for quality assurance in design, development, production, installation, and service to ensure our products meet rigorous quality standards.

We believe that we have sufficient production capacity to meet current and future demand for our product offerings through a combination of existing and added capacity, additional employees, or the outsourcing of products or components.

Compliance with Regulatory and Industry Standards

Our products must comply with a significant number of voice and data regulations and standards which vary between the U.S. and international markets, and which vary between specific international markets. Standards for new services continue to evolve, and we may need to modify our products or develop new versions to meet these standards. Standards setting and compliance verification in the U.S. are determined by the Federal Communications Commission, or FCC, Underwriters Laboratories, Quality Management Institute, Telcordia Technologies, Inc., and other communications companies. In international markets, our products must comply with standards issued by the European Telecommunications Standards Institute, or ETSI, and implemented and enforced by the telecommunications regulatory authorities of each nation.

Environmental Matters

Our operations and manufacturing processes are subject to federal, state, local and foreign environmental protection laws and regulations. These laws and regulations relate to the use, handling, storage, discharge and disposal of certain hazardous materials and wastes, the pre-treatment and discharge of process waste waters and the control of process air pollutants.

We believe that our operations and manufacturing processes currently comply in all material respects with applicable environmental protection laws and regulations. If we fail to comply with any present and future regulations, we could be subject to future liabilities, the suspension of production or a prohibition on the sale of our products. In addition, such regulations could require us to incur other significant expenses to comply with environmental regulations, including expenses associated with the redesign of any non-compliant product. From time to time new regulations are enacted, and it is difficult to anticipate how such regulations will be implemented and enforced. For example, in 2003 the European Union enacted the Restriction on the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive (RoHS) and the Waste Electrical and Electronic Equipment Directive (WEEE), for implementation in European Union member states. We are

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aware of similar legislation that is currently in force or is being considered in the United States, as well as other countries. Our failure to comply with any of such regulatory requirements or contractual obligations could result in our being liable for costs, fines, penalties and third-party claims, and could jeopardize our ability to conduct business in countries in the jurisdictions where these regulations apply.

Employees

As of December 31, 2012, we employed 267 individuals worldwide. We consider the relationships with our employees to be positive. Competition for technical personnel in our industry is intense. We believe that our future success depends in part on our continued ability to hire, assimilate and retain qualified personnel. To date, we believe that we have been successful in recruiting qualified employees, but there is no assurance that we will continue to be successful in the future.

Executive Officers

Set forth below is information concerning our executive officers and their ages as of December 31, 2012.

Morteza Ejabat is a co-founder of Zhone and has served as Chairman of the Board of Directors, President and Chief Executive Officer since June 1999. Prior to co-founding Zhone, from June 1995 to June 1999, Mr. Ejabat was President and Chief Executive Officer of Ascend Communications, Inc., a provider of telecommunications equipment which was acquired by Lucent Technologies, Inc. in June 1999. Previously, Mr. Ejabat held various senior management positions with Ascend from September 1990 to June 1995, most recently as Executive Vice President and Vice President, Operations. Mr. Ejabat holds a B.S. in Industrial Engineering and an M.S. in Systems Engineering from California State University at Northridge and an M.B.A. from Pepperdine University.

Kirk Misaka has served as Zhone’s Corporate Treasurer since November 2000 and as Chief Financial Officer and Secretary since July 2003. Prior to joining Zhone, Mr. Misaka was a Certified Public Accountant with KPMG LLP from 1980 to 2000, becoming a partner in 1989. Mr. Misaka earned a B.S. and an M.S. in Accounting from the University of Utah, and an M.S. in Tax from Golden Gate University.

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Set forth below and elsewhere in this report and in other documents we file with the SEC are risks and uncertainties that could cause actual results to differ materially from the results contemplated by the forward-looking statements contained in this report.

Our future operating results are difficult to predict and our stock price may continue to be volatile.

As a result of a variety of factors discussed in this report, our revenues for a particular quarter are difficult to predict. Our revenue and operating results may vary significantly from quarter to quarter due to a number of factors, many of which are outside of our control. The primary factors that may affect our results of operations include the following:

Any of the foregoing factors, or any other factors discussed elsewhere herein, could have a material adverse effect on our business, results of operations, and financial condition that could adversely affect our stock price. In addition, public stock markets have experienced, and may in the future experience, extreme price and trading volume volatility, particularly in the technology sectors of the market. This volatility has significantly affected the market prices of securities of many technology companies for reasons frequently unrelated to or disproportionately impacted by the operating performance of these companies. These broad market fluctuations may adversely affect the market price of our common stock. In addition, if our average market capitalization falls below the carrying value of our assets for an extended period of time as it did in 2011 and 2012, this may indicate that the fair value of our net assets is below their carrying value, and may result in recording impairment charges.

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Our common stock may be delisted from the Nasdaq Capital Market, which could negatively impact the price of our common stock and our ability to access the capital markets.

Our common stock is listed on the Nasdaq Capital Market. On June 21, 2012, we received a letter from The Nasdaq Stock Market, or Nasdaq, indicating that, for the last 30 consecutive business days preceding the date of the letter, the bid price of our common stock had closed below the $1.00 minimum per share bid price required for continued inclusion on the Nasdaq Capital Market under Marketplace Rule 5550(a)(2). In accordance with Marketplace Rule 5810(c)3)(A), we were given 180 calendar days from the date of the Nasdaq letter, or until December 18, 2012, to regain compliance with the minimum bid price rule. On December 19, 2012, we received a letter from Nasdaq advising us that we had been granted an additional 180 calendar days to regain compliance with the minimum bid price rule, or until June 17, 2013.

To regain compliance, the closing bid price of our common stock must be at or above $1.00 per share for a minimum of 10 consecutive business days. Nasdaq may, in its discretion, require us to maintain a bid price of at least $1.00 per share for a period in excess of 10 consecutive business days, but generally no more than 20 consecutive business days, before determining that we have demonstrated an ability to maintain long-term compliance. Although our stock price closed above $1.00 between February 19, 2013 and February 25, 2013, there can be no assurance that our stock price will close above the minimum bid price for a consecutive period that is long enough to regain compliance. If we do not regain compliance by June 17, 2013, Nasdaq may provide notice that our common stock will be subject to delisting. We would then have the right to appeal the delisting determination to a Nasdaq Hearings Panel. There can be no assurances that we will be able to regain compliance with the Nasdaq minimum bid price rule and thereby maintain the listing of our common stock.

Delisting from the Nasdaq Capital Market could have an adverse effect on our business and on the trading of our common stock. If a delisting of our common stock were to occur, our common stock would trade on the OTC Bulletin Board or on the “pink sheets” maintained by the National Quotation Bureau, Inc. Such alternatives are generally considered to be less efficient markets, and our stock price, as well as the liquidity of our common stock, may be adversely impacted as a result. Delisting from the Nasdaq Capital Market could also have other negative results, including the potential loss of confidence by suppliers and employees, the loss of institutional investor interest and fewer business development opportunities.

We have incurred significant losses to date and expect that we may continue to incur losses in the foreseeable future. If we fail to generate sufficient revenue to achieve or sustain profitability, our stock price could decline.

We have incurred significant losses to date and expect that we may continue to incur losses in the foreseeable future. Our net losses for 2012 and 2011 were $9.0 million and $11.7 million, respectively, and we had an accumulated deficit of $1,041.1 million at December 31, 2012. We have significant fixed expenses and expect that we will continue to incur substantial manufacturing, research and product development, sales and marketing, customer support, administrative and other expenses in connection with the ongoing development of our business. In addition, we may be required to spend more on research and product development than originally budgeted to respond to industry trends. We may also incur significant new costs related to acquisitions and the integration of new technologies and other acquisitions that may occur in the future. We may not be able to adequately control costs and expenses or achieve or maintain adequate operating margins. As a result, our ability to achieve and sustain profitability will depend on our ability to generate and sustain substantially higher revenue while maintaining reasonable cost and expense levels. If we fail to generate sufficient revenue to achieve or sustain profitability, we will continue to incur substantial operating losses and our stock price could decline.

We have significant debt obligations, which could adversely affect our business, operating results and financial condition.

As of December 31, 2012, we had approximately $10.0 million of total debt outstanding under our $25.0 million revolving line of credit and letter of credit facility (the WFB Facility) with Wells Fargo Bank (WFB), of which all was current. In addition, as of December 31, 2012, $12.6 million was committed as security for various

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letters of credit under the WFB Facility. We expect to make borrowings from time to time under the WFB Facility. The WFB Facility includes covenants, restrictions and financial ratios that may restrict our ability to operate our business. Our debt obligations could materially and adversely affect us in a number of ways, including:

We cannot assure you that we will be able to generate sufficient cash flow in amounts sufficient to enable us to service our debt or to meet our working capital and capital expenditure requirements. If we are unable to generate sufficient cash flow from operations or to borrow sufficient funds to service our debt, due to borrowing base restrictions or otherwise, we may be required to sell assets, reduce capital expenditures or obtain additional financing. We cannot assure you that we will be able to engage in any of these actions on reasonable terms, if at all.

If we default under the WFB Facility because of a covenant breach or otherwise, WFB may be entitled to, among other things, require the immediate repayment of all outstanding amounts and sell our assets to satisfy the obligations under the WFB Facility. We were in compliance with our covenants under our WFB Facility as of December 31, 2012. In 2010, we failed to satisfy a financial covenant under our former revolving line of credit and letter of credit facility. Although we were able to obtain a waiver with respect to that default, we cannot give assurances that we will be able to obtain a waiver should a default occur under our WFB Facility in the future. Any acceleration of amounts due could have a material adverse effect on our liquidity and financial condition.

If we are unable to obtain additional capital to fund our existing and future operations, we may be required to reduce the scope of our planned product development, and marketing and sales efforts, which would harm our business, financial condition and results of operations.

The development and marketing of new products, and the expansion of our direct sales operations and associated support personnel requires a significant commitment of resources. We may continue to incur significant operating losses or expend significant amounts of capital if:

As a result, we may need to raise substantial additional capital. Additional capital, if required, may not be available on acceptable terms, or at all. For example, U.S. credit markets have in recent years experienced significant dislocations and liquidity disruptions which caused the spreads on prospective debt financings to widen considerably. These circumstances materially impacted liquidity in debt markets, making financing terms for borrowers less attractive and resulting in the general unavailability of some forms of debt financing. Uncertainty in credit or capital markets could negatively impact our ability to access debt financing or to refinance existing indebtedness in the future on favorable terms, or at all. If additional capital is raised through

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the issuance of debt securities or other debt financing, the terms of such debt may include covenants, restrictions and financial ratios that may restrict our ability to operate our business. Weak and recessionary economic conditions in recent years have also adversely affected the trading prices of equity securities of many U.S. companies, including Zhone, which may make it more difficult or costly for us to raise capital through the issuance of common stock, preferred stock or other equity securities. If we elect to raise equity capital, this may be dilutive to existing stockholders and could reduce the trading price of our common stock. If we are unable to obtain additional capital or are required to obtain additional capital on terms that are not favorable to us, we may be required to reduce the scope of our planned product development and sales and marketing efforts beyond the reductions that we have previously taken, which could have a material adverse effect on our business, financial condition and results of operations.

Our lack of liquid funds and other sources of financing may limit our ability to maintain our existing operations, grow our business and compete effectively.

Our continued losses reduced our cash and cash equivalents in 2011 and 2012. As of December 31, 2012, we had approximately $11.1 million in cash and cash equivalents and $10.0 million outstanding under our bank lending facility. In order to meet our liquidity needs and finance our capital expenditures and working capital needs for our business, we may be required to sell assets, or to borrow on potentially unfavorable terms. In addition, we may be required to reduce our operations in low margin regions, including reductions in headcount. We may be unable to sell assets, access additional indebtedness or undertake other actions to meet these needs. As a result, we may become unable to pay our ordinary expenses, including our debt service, on a timely basis. Our current lack of liquidity could harm us by:

We cannot be certain that additional financing, if needed, will be available on acceptable terms or at all. If we cannot raise any necessary additional financing on acceptable terms, we may not be able to fund our business expansion, take advantage of future opportunities, meet our existing debt obligations or respond to competitive pressures or unanticipated capital requirements, any of which could have a material adverse effect on our business, financial condition and results of operations. Further, if we issue additional equity or debt securities, stockholders may experience additional dilution or the new equity securities may have rights, preference or privileges senior to those of existing holders of our common stock.

We face a number of risks related to continued weak economic and market conditions.

Global market and economic conditions in recent years have been unprecedented and challenging, with most major economies experiencing tighter credit conditions and an economic recession. Continued market turbulence and weak economic conditions, as well as concerns about energy costs, geopolitical issues, the availability and cost of credit, and the global housing and mortgage markets have contributed to continued market volatility and weak economic growth in most major economies. These conditions, combined with volatile oil prices, low business and consumer confidence and continued significant unemployment, have contributed to volatility of unprecedented levels. Continued weak economic and market conditions globally could impact our business in a number of ways, including:

Potential deferment of purchases and orders by customers: Uncertainty about current and future global economic conditions may cause consumers, businesses and governments to defer purchases in response to continued flat revenue budgets, tighter credit, decreased cash availability and weak consumer confidence. Accordingly, future demand for our products could differ materially from our current expectations.

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Customers’ inability to obtain financing to make purchases from Zhone and/or maintain their business: Some of our customers require substantial financing in order to finance their business operations, including capital expenditures on new equipment and equipment upgrades, and make purchases from Zhone. The potential inability of these customers to access the capital needed to finance purchases of our products and meet their payment obligations to us could adversely impact our financial condition and results of operations. If our customers become insolvent due to market and economic conditions or otherwise, it could have a material adverse impact on our business, financial condition and results of operations.

Negative impact from increased financial pressures on third-party dealers, distributors and retailers: We make sales in certain regions through third-party dealers, distributors and retailers. These third parties may be impacted, among other things, by the significant decrease in available credit in recent years. If credit pressures or other financial difficulties result in insolvency for these third parties and we are unable to successfully transition end customers to purchase our products from other third parties, or from us directly, it could adversely impact our financial condition and results of operations.

Negative impact from increased financial pressures on key suppliers: Our ability to meet customers’ demands depends, in part, on our ability to obtain timely and adequate delivery of quality materials, parts and components from our suppliers. Certain of our components are available only from a single source or limited sources. If certain key suppliers were to become capacity constrained or insolvent, it could result in a reduction or interruption in supplies or a significant increase in the price of supplies and adversely impact our financial condition and results of operations. In addition, credit constraints of key suppliers could result in accelerated payment of accounts payable by Zhone, impacting our cash flow.

If weak economic, market and geopolitical conditions in the United States and the rest of the world continue or worsen, we may experience material adverse impacts on our business, operating results and financial condition.

If demand for our SLMS products does not develop, then our results of operations and financial condition will be adversely affected.

Our future revenue depends significantly on our ability to successfully develop, enhance and market our SLMS products to the network service provider market. Most network service providers have made substantial investments in their current infrastructure, and they may elect to remain with their current architectures or to adopt new architectures, such as SLMS, in limited stages or over extended periods of time. A decision by a customer to purchase our SLMS products will involve a significant capital investment. We must convince our service provider customers that they will achieve substantial benefits by deploying our products for future upgrades or expansions. We do not know whether a viable market for our SLMS products will develop or be sustainable. If this market does not develop or develops more slowly than we expect, our business, financial condition and results of operations will be seriously harmed.

We depend upon the development of new products and enhancements to existing products, and if we fail to predict and respond to emerging technological trends and customers’ changing needs, our operating results and market share may suffer.

The markets for our products are characterized by rapidly changing technology, evolving industry standards, changes in end-user requirements, frequent new product introductions and changes in communications offerings from network service provider customers. Our future success depends on our ability to anticipate or adapt to such changes and to offer, on a timely and cost-effective basis, products that meet changing customer demands and industry standards. We may not have sufficient resources to successfully and accurately anticipate customers’ changing needs and technological trends, manage long development cycles or develop, introduce and market new products and enhancements. The process of developing new technology is complex and uncertain, and if we fail to develop new products or enhancements to existing products on a timely and cost-effective basis, or if our new products or enhancements fail to achieve market acceptance, our business, financial condition and results of operations would be materially adversely affected.

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Because our products are complex and are deployed in complex environments, our products may have defects that we discover only after full deployment by our customers, which could seriously harm our business.

We produce highly complex products that incorporate leading-edge technology, including both hardware and software. Software typically contains defects or programming flaws that can unexpectedly interfere with expected operations. In addition, our products are complex and are designed to be deployed in large quantities across complex networks. Because of the nature of these products, they can only be fully tested when completely deployed in large networks with high amounts of traffic, and there is no assurance that our pre-shipment testing programs will be adequate to detect all defects. As a result, our customers may discover errors or defects in our hardware or software, or our products may not operate as expected, after they have been fully deployed by our customers. If we are unable to cure a product defect, we could experience damage to our reputation, reduced customer satisfaction, loss of existing customers and failure to attract new customers, failure to achieve market acceptance, reduced sales opportunities, loss of revenue and market share, increased service and warranty costs, diversion of development resources, legal actions by our customers, and increased insurance costs. Defects, integration issues or other performance problems in our products could also result in financial or other damages to our customers. Our customers could seek damages for related losses from us, which could seriously harm our business, financial condition and results of operations. A product liability claim brought against us, even if unsuccessful, would likely be time consuming and costly. The occurrence of any of these problems would seriously harm our business, financial condition and results of operations.

A shortage of adequate component supply or manufacturing capacity could increase our costs or cause a delay in our ability to fulfill orders, and our failure to estimate customer demand properly may result in excess or obsolete component inventories that could adversely affect our gross margins.

Occasionally, we may experience a supply shortage, or a delay in receiving, certain component parts as a result of strong demand for the component parts and/or capacity constraints or other problems experienced by suppliers. If shortages or delays persist, the price of these components may increase, or the components may not be available at all, and we may also encounter shortages if we do not accurately anticipate our needs. Conversely, we may not be able to secure enough components at reasonable prices or of acceptable quality to build new products in a timely manner in the quantities or configurations needed. Accordingly, our revenue and gross margins could suffer until other sources can be developed. Our operating results would also be adversely affected if, anticipating greater demand than actually develops, we commit to the purchase of more components than we need. Furthermore, as a result of binding price or purchase commitments with suppliers, we may be obligated to purchase components at prices that are higher than those available in the current market. In the event that we become committed to purchase components at prices in excess of the current market price when the components are actually used, our gross margins could decrease. In the past we experienced component shortages that adversely affected our financial results and in the future may continue to experience component shortages.

We rely on contract manufacturers for a portion of our manufacturing requirements.

We rely on contract manufacturers to perform a portion of the manufacturing operations for our products. These contract manufacturers build product for other companies, including our competitors. In addition, we do not have contracts in place with some of these providers and may not be able to effectively manage those relationships. We cannot be certain that our contract manufacturers will be able to fill our orders in a timely manner. We face a number of risks associated with this dependence on contract manufacturers including reduced control over delivery schedules, the potential lack of adequate capacity during periods of excess demand, poor manufacturing yields and high costs, quality assurance, increases in prices, and the potential misappropriation of our intellectual property. We have experienced in the past, and may experience in the future, problems with our contract manufacturers, such as inferior quality, insufficient quantities and late delivery of products.

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We depend on a limited source of suppliers for several key components. If we are unable to obtain these components on a timely basis, we will be unable to meet our customers’ product delivery requirements, which would harm our business.

We currently purchase several key components from a limited number of suppliers. If any of our limited source of suppliers become insolvent, cease business or experience capacity constraints, work stoppages or any other reduction or disruption in output, they may be unable to meet our delivery schedules. Our suppliers may enter into exclusive arrangements with our competitors, be acquired by our competitors, stop selling their products or components to us at commercially reasonable prices, refuse to sell their products or components to us at any price or be unable to obtain or have difficulty obtaining components for their products from their suppliers. If we do not receive critical components from our limited source of suppliers in a timely manner, we will be unable to meet our customers’ product delivery requirements. Any failure to meet a customer’s delivery requirements could materially adversely affect our business, operating results and financial condition and could materially damage customer relationships.

Our target customer base is concentrated, and the loss of one or more of our customers could harm our business.

The target customers for our products are network service providers that operate voice, data and video communications networks. There are a limited number of potential customers in our target market. Axtel accounted for 10% of net revenue in 2012 and 9% of net revenue in 2011. Etisalat accounted for 8% of net revenue in 2012 and 15% of net revenue in 2011. We expect that a significant portion of our future revenue will depend on sales of our products to a limited number of customers. As a result, our revenue for any quarter may be subject to significant volatility based on changes in orders from one or a small number of key customers. Any failure of one or more customers to purchase products from us for any reason, including any downturn in their businesses, would seriously harm our business, financial condition and results of operations.

Industry consolidation may lead to increased competition and may harm our operating results.

There has been a trend toward industry consolidation in the communications equipment market for several years. We expect this trend to continue as companies attempt to strengthen or hold their market positions in an evolving industry and as companies are acquired or are unable to continue operations. We believe that industry consolidation may result in stronger competitors that are better able to compete as sole-source vendors for customers. This could have a material adverse effect on our business, financial condition and results of operations. Furthermore, rapid consolidation could result in a decrease in the number of customers we serve. Loss of a major customer could have a material adverse effect on our business, financial condition and results of operations.

We are exposed to the credit risk of some of our customers and to credit exposures in weakened markets, which could result in material losses.

Recent industry and economic conditions have weakened the financial position of some of our customers and their ability to access capital to finance their business operations, including capital expenditures. To sell to some of these customers, we may be required to assume incremental risks of uncollectible accounts or to extend credit or credit support. While we monitor these situations carefully and attempt to take appropriate measures to protect ourselves, including factoring credit arrangements to financial institutions, it is possible that we may have to defer revenue until cash is collected or write-down or write-off uncollectible accounts. Such write-downs or write-offs, if large, could have a material adverse effect on our results of operations and financial condition.

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The market we serve is highly competitive and we may not be able to compete successfully.

Competition in the communications equipment market is intense. This market is characterized by rapid change, converging technologies and a migration to networking solutions that offer superior advantages. We are aware of many companies in related markets that address particular aspects of the features and functions that our products provide. Currently, our primary competitors include Alcatel-Lucent, Calix, Adtran, Huawei, and ZTE, among others. We also may face competition from other large communications equipment companies or other companies that may enter our market in the future. In addition, a number of companies have introduced products that address the same network needs that our products address, both domestically and abroad. Many of our competitors have longer operating histories, greater name recognition, larger customer bases and greater financial, technical, sales and marketing resources than we do and may be able to undertake more extensive marketing efforts, adopt more aggressive pricing policies and provide more customer financing than we can. In particular, we are encountering price-focused competitors from Asia, especially China, which places pressure on us to reduce our prices. If we are forced to reduce prices in order to secure customers, we may be unable to sustain gross margins at desired levels or achieve profitability. Competitive pressures could result in increased pricing pressure, reduced profit margins, increased sales and marketing expenses and failure to increase, or the loss of, market share, any of which could reduce our revenue and adversely affect our financial results. Moreover, our competitors may foresee the course of market developments more accurately than we do and could develop new technologies that render our products less valuable or obsolete.

In our markets, principal competitive factors include:

If we are unable to compete successfully against our current and future competitors, we may have difficulty obtaining or retaining customers, and we could experience price reductions, order cancellations, increased expenses and reduced gross margins, any of which could have a material adverse effect on our business, financial condition and results of operations.

Our success largely depends on our ability to retain and recruit key personnel, and any failure to do so would harm our ability to meet key objectives.

Our future success depends upon the continued services of our executive officers and our ability to identify, attract and retain highly skilled technical, managerial, sales and marketing personnel who have critical industry experience and relationships that we rely on to build our business, including Morteza Ejabat, our co-founder, Chairman, President and Chief Executive Officer, and Kirk Misaka, our Chief Financial Officer. The loss of the services of any of our key employees, including Messrs. Ejabat and Misaka, could delay the development and production of our products and negatively impact our ability to maintain customer relationships, which would harm our business, financial condition and results of operations.

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Any strategic acquisitions or investments we make could disrupt our operations and harm our operating results.

As of December 31, 2012, we had acquired twelve companies or product lines since we were founded in 1999. Further, we may acquire additional businesses, products or technologies in the future. On an ongoing basis, we may evaluate acquisitions of, or investments in, complementary companies, products or technologies to supplement our internal growth. Also, in the future, we may encounter difficulties identifying and acquiring suitable acquisition candidates on reasonable terms.

If we do complete future acquisitions, we could:

Any acquisitions or investments that we make in the future will involve numerous risks, including:

Mergers and acquisitions of high-technology companies are inherently risky and subject to many factors outside of our control, and we cannot be certain that our previous or future acquisitions will be successful and will not materially adversely affect our business, operating results or financial condition. We do not know whether we will be able to successfully integrate the businesses, products, technologies or personnel that we might acquire in the future or that any strategic investments we make will meet our financial or other investment objectives. Any failure to do so could seriously harm our business, financial condition and results of operations.

Sales to communications service providers are especially volatile, and weakness in sales orders from this industry may harm our operating results and financial condition.

Sales activity in the service provider industry depends upon the stage of completion of expanding network infrastructures, the availability of funding, and the extent to which service providers are affected by regulatory, economic and business conditions in the country of operations. Although some service providers may be

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increasing capital expenditures over the depressed levels that have prevailed over the last few years, weakness in orders from this industry could have a material adverse effect on our business, operating results and financial condition. Slowdowns in the general economy, overcapacity, changes in the service provider market, regulatory developments and constraints on capital availability have had a material adverse effect on many of our service provider customers, with many of these customers going out of business or substantially reducing their expansion plans. These conditions have materially harmed our business and operating results, and we expect that some or all of these conditions may continue for the foreseeable future. Finally, service provider customers typically have longer implementation cycles; require a broader range of service including design services; demand that vendors take on a larger share of risks; often require acceptance provisions, which can lead to a delay in revenue recognition; and expect financing from vendors. All these factors can add further risk to business conducted with service providers.

Decreased effectiveness of share-based compensation could adversely affect our ability to attract and retain employees.

We have historically used stock options as a key component of our employee compensation program in order to align the interests of our employees with the interests of our stockholders, encourage employee retention and provide competitive compensation and benefit packages. If the trading price of our common stock declines, this would reduce the value of our share-based compensation to our present employees and could affect our ability to retain existing or attract prospective employees. For example, significant declines in our stock price in 2008 caused some of our employee stock options to have an exercise price significantly in excess of our stock price. To address this issue, in the fourth quarter of 2008, we conducted an exchange offer, or the Exchange Offer, in which eligible employees, officers and directors of Zhone could exchange outstanding options to purchase shares of Zhone common stock on a one-for-one basis for the grant of new options to purchase shares of Zhone common stock. Difficulties relating to obtaining stockholder approval of equity compensation plans could also make it harder or more expensive for us to grant share-based payments to employees in the future.

Due to the international nature of our business, political or economic changes or other factors in a specific country or region could harm our future revenue, costs and expenses and financial condition.

We currently have international operations consisting of sales and technical support teams in various locations around the world. We expect to continue expanding our international operations in the future. The successful management and expansion of our international operations requires significant human effort and the commitment of substantial financial resources. Further, our international operations may be subject to certain risks and challenges that could harm our operating results, including:

Any of these factors could harm our existing international operations and business or impair our ability to continue expanding into international markets.

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Compliance or the failure to comply with current and future environmental regulations could cause us significant expense.

We are subject to a variety of federal, state, local and foreign environmental regulations. If we fail to comply with any present and future regulations, we could be subject to future liabilities, the suspension of production or a prohibition on the sale of our products. In addition, such regulations could require us to incur other significant expenses to comply with environmental regulations, including expenses associated with the redesign of any non-compliant product. From time to time new regulations are enacted, and it is difficult to anticipate how such regulations will be implemented and enforced. For example, in 2003 the European Union enacted the Restriction on the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive (RoHS) and the Waste Electrical and Electronic Equipment Directive (WEEE), for implementation in European Union member states. We are aware of similar legislation that is currently in force or is being considered in the United States, as well as other countries, such as Japan and China. Our failure to comply with any of such regulatory requirements or contractual obligations could result in our being liable for costs, fines, penalties and third-party claims, and could jeopardize our ability to conduct business in countries in the jurisdictions where these regulations apply.

Adverse resolution of litigation may harm our operating results or financial condition.

We are a party to various lawsuits and claims in the normal course of our business. Litigation can be expensive, lengthy, and disruptive to normal business operations. Moreover, the results of complex legal proceedings are difficult to predict. An unfavorable resolution of a particular lawsuit could have a material adverse effect on our business, operating results and financial condition. For additional information regarding litigation in which we are involved, see Item 3, “Legal Proceedings,” contained in Part I of this report.

Our intellectual property rights may prove difficult to protect and enforce.

We generally rely on a combination of copyrights, patents, trademarks and trade secret laws and restrictions on disclosure to protect our intellectual property rights. We also enter into confidentiality or license agreements with our employees, consultants and corporate partners, and control access to and distribution of our proprietary information. Despite our efforts to protect our proprietary rights, unauthorized parties may attempt to copy or otherwise obtain and use our products or technology. Monitoring unauthorized use of our technology is difficult, and we do not know whether the steps we have taken will prevent unauthorized use of our technology, particularly in foreign countries where the laws may not protect our proprietary rights as extensively as in the United States. We cannot assure you that our pending, or any future, patent applications will be granted, that any existing or future patents will not be challenged, invalidated, or circumvented, or that any existing or future patents will be enforceable. While we are not dependent on any individual patents, if we are unable to protect our proprietary rights, we may find ourselves at a competitive disadvantage to others who need not incur the substantial expense, time and effort required to create the innovative products.

We may be subject to intellectual property infringement claims that are costly and time consuming to defend and could limit our ability to use some technologies in the future.

Third parties have in the past and may in the future assert claims or initiate litigation related to patent, copyright, trademark and other intellectual property rights to technologies and related standards that are relevant to us. The asserted claims or initiated litigation can include claims against us or our manufacturers, suppliers or customers alleging infringement of their proprietary rights with respect to our existing or future products, or components of those products. We have received correspondence from companies claiming that many of our products are using technology covered by or related to the intellectual property rights of these companies and inviting us to discuss licensing arrangements for the use of the technology. Regardless of the merit of these claims, intellectual property litigation can be time consuming and costly, and result in the diversion of technical and management personnel. Any such litigation could force us to stop selling, incorporating or using our products that include the challenged intellectual property, or redesign those products that use the technology. In

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addition, if a party accuses us of infringing upon its proprietary rights, we may have to enter into royalty or licensing agreements, which may not be available on terms acceptable to us, if at all. If we are unsuccessful in any such litigation, we could be subject to significant liability for damages and loss of our proprietary rights. Any of these results could have a material adverse effect on our business, financial condition and results of operations.

We rely on the availability of third party licenses.

Many of our products are designed to include software or other intellectual property licensed from third parties. It may be necessary in the future to seek or renew licenses relating to various elements of the technology used to develop these products. We cannot assure you that our existing and future third-party licenses will be available to us on commercially reasonable terms, if at all. Our inability to maintain or obtain any third-party license required to sell or develop our products and product enhancements could require us to obtain substitute technology of lower quality or performance standards, or at greater cost.

The long and variable sales cycles for our products may cause revenue and operating results to vary significantly from quarter to quarter.

The target customers for our products have substantial and complex networks that they traditionally expand in large increments on a periodic basis. Accordingly, our marketing efforts are focused primarily on prospective customers that may purchase our products as part of a large-scale network deployment. Our target customers typically require a lengthy evaluation, testing and product qualification process. Throughout this process, we are often required to spend considerable time and incur significant expense educating and providing information to prospective customers about the uses and features of our products. Even after a company makes the final decision to purchase our products, it may deploy our products over extended periods of time. The timing of deployment of our products varies widely, and depends on a number of factors, including our customers’ skill sets, geographic density of potential subscribers, the degree of configuration and integration required to deploy our products, and our customers’ ability to finance their purchase of our products as well as their operations. As a result of any of these factors, our revenue and operating results may vary significantly from quarter to quarter.

Our industry is subject to government regulations, which could harm our business.

Our operations are subject to various laws and regulations, including those regulations promulgated by the FCC. The FCC has jurisdiction over the entire communications industry in the United States and, as a result, our existing and future products and our customers’ products are subject to FCC rules and regulations. Changes to current FCC rules and regulations and future FCC rules and regulations could negatively affect our business. The uncertainty associated with future FCC decisions may cause network service providers to delay decisions regarding their capital expenditures for equipment for broadband services. In addition, international regulatory bodies establish standards that may govern our products in foreign markets. The SEC has adopted disclosure rules regarding the use of “conflict minerals” mined from the Democratic Republic of Congo and adjoining countries (DRC) and procedures regarding a manufacturer’s efforts to prevent the sourcing of such conflict minerals. These rules may have the effect of reducing the pool of suppliers who can supply DRC “conflict free” components and parts, and we may not be able to obtain DRC conflict free products or supplies in sufficient quantities for our operations. Also, we may face reputational challenges with our customers, stockholders and other stakeholders if we are unable to sufficiently verify the origins for the conflict minerals used in our products. We are unable to predict the scope, pace or financial impact of government regulations and other policy changes that could be adopted in the future, any of which could negatively impact our operations and costs of doing business. Because of our smaller size, legislation or governmental regulations can significantly increase our costs and affect our competitive position. Changes to or future domestic and international regulatory requirements could result in postponements or cancellations of customer orders for our products and services, which would harm our business, financial condition and results of operations. Further, we cannot be certain that we will be successful in obtaining or maintaining regulatory approvals that may, in the future, be required to operate our business.

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The ability of unaffiliated stockholders to influence key transactions, including changes of control, may be limited by significant insider ownership, provisions of our charter documents and provisions of Delaware law.

At December 31, 2012, our executive officers, directors and entities affiliated with them beneficially owned, in the aggregate, approximately 27% of our outstanding common stock. These stockholders, if acting together, will be able to influence substantially all matters requiring approval by our stockholders, including the election of directors and the approval of mergers or other business combination transactions. Circumstances may arise in which the interests of these stockholders could conflict with the interests of our other stockholders. These stockholders could delay or prevent a change in control of our company even if such a transaction would be beneficial to our other stockholders. In addition, provisions of our certificate of incorporation, bylaws and Delaware law could make it more difficult for a third party to acquire us, even if doing so would be beneficial to certain stockholders.

Our business and operations are especially subject to the risks of earthquakes and other natural catastrophic events.

Our corporate headquarters, including a significant portion of our research and development operations, are located in Northern California, a region known for seismic activity. Additionally, some of our facilities, including our manufacturing facilities, are located near geographic areas that have experienced hurricanes in the past. A significant natural disaster, such as an earthquake, hurricane, fire, flood or other catastrophic event, could severely affect our ability to conduct normal business operations, and as a result, our future operating results could be materially and adversely affected.

None.

Our worldwide headquarters are located in Oakland, California. In September 2010, we sold the land and buildings in Oakland, California which we had previously owned. As part of the sale transaction, we leased back one of the three buildings which is used for our executive offices, research and product development activities, and administrative and marketing activities.

In addition to our Oakland headquarters, we also lease facilities for manufacturing, research and development purposes at locations including Largo, Florida; Alpharetta, Georgia; and Westlake Village, California. We also maintain smaller offices to provide sales and customer support at various domestic and international locations. We believe that our existing facilities are suitable and adequate for our present purposes.

We are subject to various legal proceedings, claims and litigation arising in the ordinary course of business. While the outcome of these matters is currently not determinable, we do not expect that the ultimate costs to resolve these matters will have a material adverse effect on our consolidated financial position or results of operations. However, litigation is subject to inherent uncertainties, and unfavorable rulings could occur. If an unfavorable ruling were to occur, there exists the possibility of a material adverse impact on the results of operations of the period in which the ruling occurs, or future periods.

Not applicable.

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PART II

Price Range of Common Stock

Our common stock is listed on the Nasdaq Capital Market under the symbol “ZHNE.” The following table sets forth, for the periods indicated, the high and low per share sales prices of our common stock as reported on Nasdaq.

As of March 1, 2013, there were 1,316 registered stockholders of record. A substantially greater number of holders of Zhone common stock are “street name” or beneficial holders, whose shares are held of record by banks, brokers and other financial institutions.

Dividend Policy

We have never paid or declared any cash dividends on our common stock or other securities and do not anticipate paying cash dividends in the foreseeable future. Any future determination to pay cash dividends will be at the discretion of the Board of Directors, subject to any applicable restrictions under our debt and credit agreements, and will be dependent upon our financial condition, results of operations, capital requirements, general business condition and such other factors as the Board of Directors may deem relevant.

Recent Sales of Unregistered Securities

There were no unregistered sales of equity securities during 2012.

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The following selected financial data has been derived from our consolidated financial statements and should be read in conjunction with the consolidated financial statements and notes thereto, and with “Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

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Overview

We believe that we are the first company dedicated solely to developing the full spectrum of next-generation access network solutions to cost-effectively deliver high bandwidth services while simultaneously preserving the investment in today’s networks. Our next-generation solutions are based upon our SLMS architecture. From its inception, this SLMS architecture was specifically designed for the delivery of multiple classes of subscriber services (such as voice, data and video distribution), rather than being based on a particular protocol or media. In other words, our SLMS products are built to support the migration from legacy circuit to packet technologies and from copper to fiber technologies. This flexibility and versatility allows our products to adapt to future technologies while allowing service providers to focus on the delivery of additional high bandwidth services. Because this SLMS architecture is designed to interoperate with existing legacy equipment, service providers can leverage their existing networks to deliver a combination of voice, data and video services today, while they migrate, either simultaneously or at a future date, from legacy equipment to next-generation equipment with minimal interruption. We believe that our SLMS solution provides an evolutionary path for service providers from their existing infrastructures, as well as gives newer service providers the capability to deploy cost-effective, multi-service networks that can support voice, data and video.

Our global customer base includes regional, national and international telecommunications carriers. To date, our products are deployed by over 750 network service providers on six continents worldwide. We believe that we have assembled the employee base, technological breadth and market presence to provide a simple yet comprehensive set of next-generation solutions to the bandwidth bottleneck in the access network and the other problems encountered by network service providers when delivering communications services to subscribers.

Since inception, we have incurred significant operating losses and had an accumulated deficit of $1,041.1 million as of December 31, 2012, and we expect that our operating losses and negative cash flows from operations may continue. If we are unable to access or raise the capital needed to meet liquidity needs and finance capital expenditures and working capital, or if the economic, market and geopolitical conditions in the United States and the rest of the world do not improve or if they deteriorate, we may experience material adverse impacts on our business, operating results and financial condition. During 2009, we implemented several activities intended to reduce costs, improve operating efficiencies and change our operations to more closely align them with our key strategic focus, which included headcount reductions. During the past three years, we have continued our focus on cost control and operating efficiency along with restrictions on discretionary spending. The most significant cost-cutting measure during 2010 was the sale in September 2010 of our land and buildings located in Oakland, California and extinguishment of related debt in a sale and leaseback transaction with LBA Realty, LLC, or LBA Realty. The sale and leaseback transaction allowed us to reduce occupancy costs and improved our financial position by eliminating the related debt which was due in April 2011. In September 2012, we closed our development center in Portsmouth, New Hampshire to reduce occupancy and personnel-related expenses.

Going forward, our key financial objectives include the following:

Critical Accounting Policies and Estimates

Management’s discussion and analysis of financial condition and results of operations is based upon our consolidated financial statements, which have been prepared in accordance with generally accepted accounting principles in the United States of America. The preparation of these consolidated financial statements requires

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management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosure of contingent assets and liabilities. The policies discussed below are considered by management to be critical because changes in such estimates can materially affect the amount of our reported net income or loss. For all of these policies, management cautions that actual results may differ materially from these estimates under different assumptions or conditions.

Revenue Recognition

We recognize revenue when the earnings process is complete. We recognize product revenue upon shipment of product under contractual terms which transfer title to customers upon shipment, under normal credit terms, net of estimated sales returns and allowances at the time of shipment. Revenue is deferred if there are significant post-delivery obligations or if the fees are not fixed or determinable. When significant post-delivery obligations exist, revenue is deferred until such obligations are fulfilled. Our arrangements generally do not have any significant post-delivery obligations. If our arrangements include customer acceptance provisions, revenue is recognized upon obtaining the signed acceptance certificate from the customer, unless we can objectively demonstrate that the delivered products or services meet all the acceptance criteria specified in the arrangement prior to obtaining the signed acceptance. In those instances where revenue is recognized prior to obtaining the signed acceptance certificate, we use successful completion of customer testing as the basis to objectively demonstrate that the delivered products or services meet all the acceptance criteria specified in the arrangement. We also consider historical acceptance experience with the customer, as well as the payment terms specified in the arrangement, when revenue is recognized prior to obtaining the signed acceptance certificate. When collectability is not reasonably assured, revenue is recognized when cash is collected.

We make certain sales to product distributors. These customers are given certain privileges to return a portion of inventory. Return privileges generally allow distributors to return inventory based on a percent of purchases made within a specific period of time. We recognize revenue on sales to distributors that have contractual return rights when the products have been sold by the distributors, unless there is sufficient customer specific sales and sales returns history to support revenue recognition upon shipment. In those instances when revenue is recognized upon shipment to distributors, we use historical rates of return from the distributors to provide for estimated product returns. We accrue for warranty costs, sales returns and other allowances at the time of shipment based on historical experience and expected future costs.

We derive revenue primarily from stand-alone sales of our products. In certain cases, our products are sold along with services, which include education, training, installation, and/or extended warranty services. As such, some of our sales have multiple deliverables. Our products and services qualify as separate units of accounting and are deemed to be non-contingent deliverables as our arrangements typically do not have any significant performance, cancellation, termination and refund type provisions. Products are typically considered delivered upon shipment. Revenue from services is recognized ratably over the period during which the services are to be performed.

For multiple deliverable revenue arrangements, we allocate revenue to products and services using the relative selling price method to recognize revenue when the revenue recognition criteria for each deliverable are met. The selling price of a deliverable is based on a hierarchy and if we are unable to establish vendor-specific objective evidence of selling price (VSOE) we look to third-party evidence of selling price (TPE) and if no such data is available, we use a best estimated selling price (BSP). In most instances, particularly as it relates to products, we are not able to establish VSOE for all deliverables in an arrangement with multiple elements. This may be due to infrequently selling each element separately, not pricing products within a narrow range, or only having a limited sales history. When VSOE cannot be established, we attempt to establish the selling price of each element based on TPE. Generally, our marketing strategy differs from that of our peers and our offerings contain a significant level of customization and differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. Therefore, we are typically not able to determine TPE for our products.

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When we are unable to establish selling price using VSOE or TPE, we use BSP. The objective of BSP is to determine the price at which we would transact a sale if the product or service were sold on a stand-alone basis. The BSP of each deliverable is determined using average discounts from list price from historical sales transactions or cost plus margin approaches based on the factors, including but not limited to our gross margin objectives and pricing practices plus customer and market specific considerations.

We have established TPE for our training, education and installation services. These service arrangements are typically short term in nature and are largely completed shortly after delivery of the product. TPE is determined based on competitor prices for similar deliverables when sold separately. Training and education services are based on a daily rate per person and vary according to the type of class offered. Installation services are based on daily rate per person and vary according to the complexity of the products being installed.

Extended warranty services are priced based on the type of product and are sold in one to five year durations. Extended warranty services include the right to warranty coverage beyond the standard warranty period. In substantially all of the arrangements with multiple deliverables pertaining to arrangements with these services, we have used and intend to continue using VSOE to determine the selling price for the services. We determine VSOE based on our normal pricing practices for these specific services when sold separately.

Allowances for Sales Returns and Doubtful Accounts

We record an allowance for sales returns for estimated future product returns related to current period product revenue. The allowance for sales returns is recorded as a reduction of revenue and an allowance against our accounts receivable. We base our allowance for sales returns on periodic assessments of historical trends in product return rates and current approved returned products. If the actual future returns were to deviate from the historical data on which the reserve had been established, our future revenue could be adversely affected. We record an allowance for doubtful accounts for estimated losses resulting from the inability of customers to make payments for amounts owed to us. The allowance for doubtful accounts is recorded as a charge to general and administrative expenses. We base our allowance on periodic assessments of our customers’ liquidity and financial condition through analysis of information obtained from credit rating agencies, financial statement reviews and historical collection trends. Additional allowances may be required in the future if the liquidity or financial condition of our customers deteriorates, resulting in impairment in their ability to make payments.

Stock-Based Compensation

We estimate the fair value of stock-based payment awards on the date of grant using the Black Scholes pricing model, which is affected by our stock price as well as assumptions regarding a number of complex and subjective variables. These variables include our expected stock price volatility over the term of the awards, actual and projected employee option exercise behaviors, risk free interest rate and expected dividends. The expected stock price volatility is based on the weighted average of the historical volatility of our common stock over the most recent period commensurate with the estimated expected life of our stock options. We base our expected life assumption on our historical experience and on the terms and conditions of the stock awards we grant to employees. Risk free interest rates reflect the yield on zero-coupon U.S. Treasury securities. We do not anticipate paying any cash dividends in the foreseeable future and therefore use an expected dividend yield of zero.

If factors change, and we employ different assumptions for estimating stock-based compensation expense in future periods, or if we decide to use a different valuation model, the future periods may differ significantly from what we have recorded in the current period and could materially affect our operating income, net loss and net loss per share. We are also required to estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates.

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In addition, stock-based compensation expense was recorded for options issued to non-employees. These options are generally immediately exercisable and expire seven to ten years from the date of grant. We value non-employee options using the Black Scholes model. Non-employee options subject to vesting are re-valued as they become vested.

In 2008, we completed the exchange of certain stock options issued to eligible employees, officers and directors of Zhone under our equity incentive compensation plans (the Exchange Offer). On March 31, 2010, our board of directors approved the acceleration of vesting of all unvested options to purchase shares of Zhone common stock issued in connection with the Exchange Offer that were held by members of our senior management. The acceleration was effective as of March 31, 2010. Options to purchase an aggregate of approximately 0.9 million shares of Zhone common stock were subject to the acceleration and resulted in a compensation charge of $0.9 million which was fully expensed in the three-month period ended March 31, 2010. The acceleration of these options was undertaken in recognition of the achievement of certain performance objectives by our senior management.

In 2011, our board of directors approved the acceleration of vesting of all unvested options to purchase shares of Zhone common stock that were held by members of our senior management as of that date. The acceleration was effective as of September 30, 2011. Options to purchase an aggregate of approximately 0.6 million shares of Zhone common stock were subject to the acceleration and resulted in a compensation charge of $0.7 million which was fully expensed in the three-month period ended September 30, 2011. The acceleration of these options was undertaken to partially offset previous reductions in cash compensation and other benefits by our senior management.

On August 9, 2012, our board of directors approved the acceleration of vesting of all unvested options to purchase shares of Zhone common stock that were held by our senior management and employees as of that date. The acceleration for shares held by senior management was effective as of August 9, 2012 and the acceleration of shares held by all other employees was effective as of September 30, 2012. Options to purchase an aggregate of approximately 0.6 million shares of Zhone common stock were subject to the acceleration and resulted in a compensation charge of $0.7 million which was fully expensed in the three month period ended September 30, 2012. The acceleration of these options was undertaken to partially offset previous reductions in cash compensation and other benefits by our senior management and employees.

Inventories

Inventories are stated at the lower of cost or market, with cost being determined using the first-in, first-out (FIFO) method. In assessing the net realizable value of inventories, we are required to make judgments as to future demand requirements and compare these with the current or committed inventory levels. Once inventory has been written down to its estimated net realizable value, its carrying value cannot be increased due to subsequent changes in demand forecasts. To the extent that a severe decline in forecasted demand occurs, or we experience a higher incidence of inventory obsolescence due to rapidly changing technology and customer requirements, we may incur significant charges for excess inventory.

Accounting for Impairment of Long-Lived Assets

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be fully recoverable based on expected undiscounted cash flows attributable to that asset. Recoverability of assets to be held and used is measured by comparing the carrying amount of an asset to the future net undiscounted cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future net undiscounted cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. Any assets to be disposed of would be separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell, and would no longer be depreciated. The assets and liabilities of a disposed group classified as held for sale would be presented separately in the appropriate asset and liability sections of the balance sheet.

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During the year ended December 31, 2012, we recorded $0.1 million in impairment charges related to the impairment of long-lived assets as discussed in Note 4 to the consolidated financial statements.

RESULTS OF OPERATIONS

We list in the table below the historical consolidated statement of comprehensive loss as a percentage of net revenue for the periods indicated.

2012 COMPARED WITH 2011

Net Revenue

Information about our net revenue for products and services for 2012 and 2011 is summarized below (in millions):

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Information about our net revenue for North America and international markets for 2012 and 2011 is summarized below (in millions):

Net revenue decreased 7% or $9.1 million to $115.4 million for 2012 compared to $124.5 million for 2011. The decrease in net revenue was primarily attributable to a decrease in product revenue, which in 2012 decreased 8% or $9.1 million compared to 2011. The decrease was primarily due to decreased sales in our SLMS product portfolio. Service revenue remained flat at $5.1 million in 2012 and 2011. Service revenue represents revenue from maintenance and other services associated with product shipments.

International net revenue decreased 10% or $7.2 million to $64.5 million in 2012 and represented 56% of total net revenue compared with 58% in 2011. The decrease in international net revenue was primarily due to decreased sales in the Middle East and Latin America, which was partially offset by higher revenue from Asia as a result of recent growth in demand for our products in this region. Domestic net revenue decreased 4% or $1.9 million to $50.9 million in 2012 compared to $52.8 million in 2011.

Axtel accounted for 10% and 9% of net revenue in 2012 and 2011, respectively. Etisalat accounted for 8% of net revenue in 2012 and 15% of net revenue in 2011. We anticipate that our results of operations in any given period may depend to a large extent on sales to a small number of large accounts. As a result, our revenue for any quarter may be subject to significant volatility based upon changes in orders from one or a small number of key customers.

Cost of Revenue and Gross Profit

Total cost of revenue, including stock-based compensation, decreased $1.4 million or 2% to $79.1 million for 2012, compared to $80.5 million for 2011. The decrease was primarily due to a decrease in personnel expenses compared to the prior year. Total cost of revenue was 69% of net revenue for 2012, compared to 65% of net revenue for 2011, which resulted in a decrease in gross profit percentage from 35% in 2011 to 31% in 2012. The year-over-year decrease in gross margin was primarily due to decreased sales volume and the increase in cost of revenue in 2012. Cost of revenue increased primarily as a result of greater sales of products with lower gross margin, such as our GPON products.

We expect that in the future, our cost of revenue as a percentage of net revenue will vary depending on the mix and average selling prices of products sold in the future. In addition, continued competitive and economic pressures could cause us to reduce our prices, adjust the carrying values of our inventory, or record inventory charges relating to discontinued products and excess or obsolete inventory.

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Research and Product Development Expenses

Research and product development expenses decreased 13% or $2.9 million to $18.5 million for 2012 compared to $21.4 million for 2011. The decrease was primarily due to decreased depreciation expense as a result of the fixed asset impairment taken in the fourth quarter of 2011 and decreases in allocated facilities costs as well as a decrease in personnel-related expenses resulting from a lower headcount in 2012 as compared with 2011. We intend to continue to invest in research and product development to attain our strategic product development objectives while seeking to manage the associated costs through expense controls.

Sales and Marketing Expenses

Sales and marketing expenses decreased 13% or $3.0 million to $19.3 million for 2012 compared to $22.3 million for 2011. The decrease was primarily attributable to a decrease in overall sales expenses of $1.8 million compared to 2011. The decline in sales expenses was primarily due to continued reductions in travel and consulting expenses, and decreased commissions. Also, customer service expenses decreased $0.6 million compared to 2011 primarily due to a $0.5 million reduction in personnel-related costs. In addition, marketing expenses decreased $0.5 million compared to 2011, primarily due to a $0.2 million reduction in personnel-related expenses and $0.1 million in advertising. Lastly, stock-based compensation expense decreased $0.1 million compared to the prior year.

General and Administrative Expenses

General and administrative expenses decreased 8% or $0.6 million to $7.2 million for 2012 compared to $7.8 million for 2011. The decrease was primarily due to a $1.0 million gain as a result of patent sales and a $0.7 million decrease in personnel-related expenses. Also, depreciation expense decreased $0.5 million as a result of the fixed asset impairment recorded in the fourth quarter of 2011. These decreases were partially offset by increases of $0.6 million in allocated facility costs and $0.5 million in bad debt expense. In addition, a tax dispute that was settled in 2011 resulted in the reversal of an accrual of $0.4 million in 2011. There was no similar transaction in the current period.

Impairment of Fixed Assets

Impairment of fixed assets was $0.1 million for 2012 compared to $4.2 million for 2011. In 2011, our continued negative cash flows and operating losses as well as the significant decrease in the market price of our stock indicated that the book value of our fixed assets could be impaired. After determining there were indicators of impairment, we proceeded to test for impairment and concluded that an impairment charge was required in both 2012 and 2011 to write down the value of our fixed assets to fair value, as discussed in Note 4 of the consolidated financial statements.

Interest Expense

Interest expense for 2012 increased to $0.1 million compared to an immaterial balance in 2011, primarily due to a settlement of a tax dispute in 2011, resulting in the reversal of an accrual which offset interest expense by $0.1 million in 2011. Our outstanding debt balances remained constant and interest rates remained low during 2012.

Interest Income

Interest income for 2012 remained consistent with 2011 due to continued low average balances of cash and cash equivalents and continued low interest rates during 2012.

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Other Income (Expense)

Other income (expense) for 2012 decreased by $0.1 million to an immaterial balance compared to $0.1 million in 2011 due to a foreign exchange loss in the current period.

Income Tax Provision

During the years ended December 31, 2012 and 2011, we recorded an income tax provision of $0.1 million related to foreign and state taxes. No material provision or benefit for income taxes was recorded in 2012 and 2011, due to our recurring operating losses and the significant uncertainty regarding the realization of our net deferred tax assets, against which we have continued to record a full valuation allowance.

2011 COMPARED WITH 2010

Net Revenue

Information about our net revenue for products and services for 2011 and 2010 is summarized below (in millions):

Information about our net revenue for North America and international markets for 2011 and 2010 is summarized below (in millions):

Net revenue decreased 3% or $4.5 million to $124.5 million for 2011 compared to $129.0 million for 2010. The decrease in net revenue was primarily attributable to a decrease in product revenue, which in 2011 decreased 4% or $5.2 million compared to 2010. The decrease was primarily due to decreased sales in our SLMS product portfolio. Service revenue increased 16% or $0.7 million compared to 2010, primarily due to an increase in the number of service contracts accompanied by the timing of services performed and revenue earned. Service revenue represents revenue from maintenance and other services associated with product shipments.

International net revenue decreased 9% or $7.1 million to $71.7 million in 2011 and represented 58% of total net revenue compared with 61% in 2010. The decrease in international net revenue was primarily due to decreased sales in the Middle East, which was partially offset by higher revenue from Latin America as a result of recent growth in demand for our products in this region. The decrease in international net revenue was

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partially offset by an increase in domestic net revenue of 5% or $2.6 million to $52.8 million in 2011 compared to $50.2 million in 2010. The increase was primarily the result of continued relationships with customers who have been approved for broadband stimulus funding through the federal Rural Utilities Service.

Etisalat accounted for 15% and 24% of net revenue in 2011 and 2010, respectively.

Cost of Revenue and Gross Profit

Total cost of revenue, including stock-based compensation, increased $0.6 million or 1% to $80.5 million for 2011, compared to $79.9 million for 2010. The increase was primarily due to an increase in non-personnel expenses compared to the prior year. The increase was partially offset by a release of $0.8 million due to vendor liabilities identified on the consolidated balance sheet where the applicable statute of limitations had expired. Total cost of revenue was 65% of net revenue for 2011, compared to 62% of net revenue for 2010, which resulted in a decrease in gross profit percentage from 38% in 2010 to 35% in 2011. The gross margin decreased as compared with prior periods primarily due to decreased sales volume and the increase in cost of revenue for the period resulting from greater sales of products with lower gross margin, such as our GPON products.

Research and Product Development Expenses

Research and product development expenses increased 1% or $0.2 million to $21.4 million for 2011 compared to $21.2 million for 2010. The increase was primarily due to an increase in personnel related expenses resulting from a slightly higher headcount in 2011 as compared with 2010.

Sales and Marketing Expenses

Sales and marketing expenses decreased 7% or $1.7 million to $22.3 million for 2011 compared to $24.0 million for 2010. The decrease was primarily attributable to a decrease in overall sales and customer service expenses of $1.0 million compared to 2010, including decreases in salaries and travel related to customer service personnel of $0.5 million and decreases in other expenses of $0.5 million, of which $0.3 million related to lower facilities expenses resulting from the sale of the Oakland campus in September 2010. In addition, marketing expenses decreased $0.6 million compared to 2010, primarily due to a $0.4 million reduction in advertising and related materials and a $0.1 million reduction in the facilities expense. Lastly, stock-based compensation expense decreased $0.1 million compared to the prior year.

General and Administrative Expenses

General and administrative expenses decreased 21% or $2.1 million to $7.8 million for 2011 compared to $9.9 million for 2010. The main driver for the decrease was the sale of the Oakland, California campus in 2010 as discussed in Note 5 of the consolidated financial statements. As a result of this sale, general and administrative expenses decreased $1.2 million compared to 2010 from a combination of reduced property taxes, utilities, security expenses, and rent expense from the continued amortization of the gain associated with the campus sale. In addition, a tax dispute was settled in 2011, resulting in the reversal of an accrual of $0.4 million. Also, stock-based compensation expense decreased $0.4 million primarily due to the significant acceleration of unvested stock options that took place in March 2010, compared to a smaller acceleration of unvested stock options in August 2011. Lastly, there was an overall decrease of $0.1 million in various other miscellaneous expenses.

Gain on Sale of Fixed Assets

Gain on sale of fixed assets was $2.0 million for 2010. The gain in 2010 was attributable to the sale of our Oakland, California campus, consisting of land and three buildings, in September 2010, as discussed in Note 5 of the consolidated financial statements. There were no similar sales of fixed assets in 2011.

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Impairment of Fixed Assets

Impairment of fixed assets was $4.2 million for 2011. Our continued negative cash flows and operating losses as well as the significant decrease in the market price of our stock indicated that the book value of our fixed assets could be impaired. After determining there were indicators of impairment, we proceeded to test for impairment and concluded that an impairment charge was required. The impairment charges were incurred to write-down the value of our fixed assets to fair value, as discussed in Note 4 of the consolidated financial statements. There were no similar impairment charges incurred in 2010.

Interest Expense

Interest expense for 2011 decreased by $1.0 million to zero compared to $1.0 million in 2010, primarily due to a decrease in outstanding debt balances and continued low interest rates during 2011. This includes the effect of our September 2010 extinguishment of debt associated with the sale of our Oakland, California campus as discussed in Note 7 of the consolidated financial statements.

Interest Income

Interest income for 2011 remained consistent with 2010 due to continued low average balances of cash and cash equivalents and continued low interest rates during 2011.

Other Income

Other income for 2011 increased by $0.1 million to $0.1 million compared to zero in 2010 due to an increased foreign exchange gain from prior period.

Income Tax Provision

During the years ended December 31, 2011 and 2010, we recorded an income tax provision of $0.1 million and an income tax benefit of $0.1 million, respectively, related to foreign and state taxes. No material provision or benefit for income taxes was recorded in 2011 and 2010, due to our recurring operating losses and the significant uncertainty regarding the realization of our net deferred tax assets, against which we have continued to record a full valuation allowance.

OTHER PERFORMANCE MEASURES

In managing our business and assessing our financial performance, we supplement the information provided by our GAAP results with adjusted earnings before stock-based compensation, interest, taxes, and depreciation, or Adjusted EBITDA, a non-GAAP financial measure. We define Adjusted EBITDA as net income (loss) plus (i) interest expense, (ii) provision (benefit) for taxes, (iii) depreciation and amortization, (iv) non-cash equity-based compensation expense, and (v) material non-recurring non-cash transactions, such as a gain (loss) on sale of assets or impairment of fixed assets. We believe that the presentation of Adjusted EBITDA enhances the usefulness of our financial information by presenting a measure that management uses internally to monitor and evaluate our operating performance and to evaluate the effectiveness of our business strategies. We believe Adjusted EBITDA also assists investors and analysts in comparing our performance across reporting periods on a consistent basis because it excludes the impact of items that we do not believe reflect our core operating performance.

Adjusted EBITDA has limitations as an analytical tool. Some of these limitations are:

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Because of these limitations, Adjusted EBITDA should not be considered in isolation or as a substitute for net income (loss) or any other performance measures calculated in accordance with GAAP or as a measure of liquidity. Management understands these limitations and compensates for these limitations by relying primarily on our GAAP results and using Adjusted EBITDA only supplementally.

Set forth below is a reconciliation of Adjusted EBITDA to net income (loss), which we consider to be the most directly comparable GAAP financial measure to Adjusted EBITDA:

LIQUIDITY AND CAPITAL RESOURCES

Our operations are financed through a combination of our existing cash, cash equivalents, available credit facilities, and sales of equity and debt instruments, based on our operating requirements and market conditions.

At December 31, 2012, cash and cash equivalents were $11.1 million compared to $18.2 million at December 31, 2011. The decrease in cash and cash equivalents of $7.1 million was attributable to net cash used in operating activities, investing activities, and financing activities of $1.9 million, $0.3 million, and $4.9 million, respectively.