May 3, 2010—PETALUMA, CA—Calix(NYSE: CALX) today announced that Transtelco, an innovative communications service provider (CSP) serving businesses throughout northern Mexico and cities along the U.S. border, has chosen the Calix Unified Access portfolio to deliver a variety of business-focused fiber services and applications across its network. As a CSP who targets companies that do business across the border, Transtelco is moving its network "Fiber Forward" with Calix by utilizing gigabit passive optical network (GPON) and point-to-point Ethernet technologies to meet the demand for flexible and carrier class high-bandwidth services, including support for E1, T1, gigabit Ethernet, and a variety of Metro Ethernet Forum (MEF) services.

Transtelco will widely deploy the EXA Powered E7 Ethernet Service Access Platform (ESAP) and a variety of 700GX optical network terminals (ONTs) to deliver advanced services across both GPON and point-to-point Ethernet technologies to the business subscriber premises. Independent of the technology utilized, service delivered, or form factor, the Calix Management System (CMS) will provide provisioning and service management across the entire Calix Unified Access Infrastructure.

"As a CSP competing against a large incumbent operator, it is crucial for Transtelco to differentiate itself and deliver the most advanced services efficiently and effectively," said Manuel Marin, vice president of engineering and development at Transtelco. "Fiber to the premises provides us with the optimal delivery vehicle for addressing our customers' demands. The breadth and flexibility of the Calix fiber access solutions portfolio, coupled with exceptional technical support, gives us the tools we need to deliver the services our customers want with the efficiency that our business demands."

Headquartered in Ciudad Juarez, Chihuahua, Mexico, but serving most border cities along the U.S./Mexico border, Transtelco sees wide fiber deployment as key to its future. As Transtelco expands its fiber network and services, the Calix Unified Access portfolio provides the following benefits to Transtelco:

• The EXA Powered E7 brings high capacity, high density, and services flexibility via a combination of GPON and point-to-point Ethernet technologies, as well as 10 gigabit Ethernet (GE) transport services to and between Transtelco's targeted business customers.
• The Calix 700GX family of ONTs deliver a variety of form factors and service options at the customer premises, including key business services from multiple T1s to symmetrical gigabit Ethernet services with MEF feature support. Calix ONTs provide Transtelco with optimized options for a range of applications, including the ability for each ONT unit to auto-detect GPON and point-to-point technologies.
• CMS allows Transtelco to implement a unified service activation and management model across the Calix Unified Access Infrastructure, supporting multiple service types, technologies, and form factors.
• The Calix Unified Access portfolio provides Transtelco with fiber access experience and network innovation, with more than 380 CSPs across North America and now Latin America deploying Calix fiber access solutions.

"The demand for advanced fiber access and carrier class business Ethernet solutions knows no borders, and Transtelco is taking a leading role in bringing these advanced services to its customers on both sides of the border," said John Colvin, vice president of field operations at Calix. "Transtelco is moving 'Fiber Forward' by using GPON, point-to-point Ethernet, and 10GE technologies across the Calix Unified Access portfolio to help redefine the quality and capacity of service options available to its customers along the Mexico/U.S. border. We feel privileged that Transtelco has selected Calix for its strategic fiber access initiatives and become our first customer in Latin America, and we look forward to working with them to deliver some of the world's most advanced services to the businesses of this growing region."

About Transtelco

Located in the heart of the largest border region in the world, Transtelco's geographic focus includes the entire southern United States - Mexico Border. Transtelco delivers world class telecommunication services including: Transport, Direct Internet Access, Last Mile, Voice and Collocation Solutions for Carrier and Enterprise customers over a Next-Generation fiber optic platform. Our philosophy of "simplified communications" allows our clients to focus on their core business while we solve their telecommunications issues. For more information, visit us at www.transtelco.com.

About Calix

Calix is a leading provider in North America of broadband communications access systems and software for copper- and fiber- based network architectures that enable communications service providers to connect to their residential and business subscribers. Calix enables communications service providers to provide a wide range of revenue-generating services, from basic voice and data to advanced broadband services, over legacy and next-generation access networks. Calix's Unified Access Portfolio helps these companies to transform their legacy and mixed protocol access networks to fiber and Ethernet. Calix has shipped over six million ports of its Unified Access Infrastructure portfolio to more than 500 North American and international customers, whose networks serve over 32 million subscriber lines in total. For more information, visit the Calix website at www.calix.com.

This press release may contain forward-looking statements that are based upon management's current expectations and are inherently uncertain. Forward-looking statements are based upon information available to us as of the date of this release and we assume no obligation to revise or update any such forward-looking statement to reflect any event or circumstance after the date of this release, except as required by law. Actual results and the timing of events could differ materially from current expectations, based on risks and uncertainties affecting the Company's business. The reader is cautioned not to unduly rely on the forward-looking statements contained in this press release. Additional information on potential factors that could affect Calix's results and other risks and uncertainties are detailed in its prospectus, filed with the SEC on March 24, 2010, available at http://www.sec.gov.

For additional information contact:

Catherine Koo
LEWIS PR
415-992-4400
calix@lewispr.com