MAY 23, 2005, BOCA RATON, FL and PETALUMA, CA—Siemens Communications, Inc., and Calix today announced interoperability between the Calix C7 multiservice access platform and the new Siemens^® broadband passive optical network (BPON) family of solutions. The two portfolios provide standards-based, flexible and robust fiber to the premise (FTTP) optical network terminal (ONT) and optical network unit (ONU) solutions. Together, Siemens and Calix are promoting standards-compliant G.983 BPON solutions to make FTTP network deployments simpler and quicker for wireline service providers.

Operating as a BPON optical line terminal (OLT), the Calix C7 platform allows service providers to deliver an identical mix of voice, data and video services to both fiber-connected and copper wire-connected subscribers. The Siemens family of FTTP ONT/ONU products is deployable in multiple environments such as single-family residences, businesses and multi-dwelling housing units.

The combined solution allows service providers to deliver a rich array of packet-based voice, data and video services. In addition to supporting cable overlay as a video overlay method, utilizing a dedicated optical wavelength on the downstream BPON facility, the Siemens/Calix solution offers fully switched Internet Protocol Television (IPTV) services. With IPTV, service providers can offer a compelling new package of video services.

"With a standards-based approach to FTTP, service providers can independently select the best OLTs and ONTs to develop their networks to full potential," said Harald Braun president of the Carrier Networks Division for Siemens Communications, Inc. "Both Siemens and Calix are committed to delivering proven interoperable solutions that greatly simplify FTTP deployments."

"Service providers learned long ago that it is in their best interest to be able to select from a set of interoperable solutions," said Calix CEO Carl Russo. "Utilizing ONTs and ONUs from a large, stable supplier like Siemens, while taking advantage of the capacity and flexibility inherent in the Calix C7, gives providers the best of both worlds."

Interoperability between Siemens and Calix products is certified as part of the CalixCompatible Service Assurance Program. Under the terms of this program, Siemens and Calix jointly conduct ongoing interoperability testing at the large-scale, California-based CalixCompatible test labs, which include a complete video head end. The two companies will also work closely with service providers to ensure rapid and trouble-free rollout of ultra-broadband, packet-based fiber access networks.

About Calix
Calix is a leading supplier of telecommunications solutions designed to simplify all aspects of voice, data and video service delivery to business and residential subscribers for local exchange carriers of all sizes. Providing extensive optical and metallic density, unprecedented access capacity and functional headroom, advanced management and provisioning capabilities, and broad service flexibility, the packet-based Calix C7 platform has been deployed in over 150 service provider networks throughout North America. More information about Calix can be found at www.calix.com

About Siemens
Siemens AG (NYSE:SI) is one of the largest global electronics and engineering companies with reported worldwide sales of $91.5 billion in fiscal 2004. Founded more than 150 years ago, the company is a leader in the areas Medical, Power, Automation and Control, Transportation, Information and Communications, Lighting, Building Technologies, Water Technologies and Services and Home Appliances. With its U.S. corporate headquarters in New York City, Siemens in the USA has sales of $16.6 billion and employs 70,000 people throughout all 50 states and Puerto Rico. Thirteen of Siemens' worldwide businesses are based in the United States. With its global headquarters in Munich, Siemens AG and its subsidiaries employ 430,000 people in 192 countries. For more information on Siemens in the United States: www.usa.siemens.com

About Siemens Communications, Inc.
Siemens Communications, Inc., offers its customers a broad portfolio of communication products and services and is a leader in convergent technologies, products and services for wireless, fixed and enterprise networks. The company's portfolio ranges from devices for end users to complex network infrastructures and complementary services for enterprises, carriers and service providers. Siemens Communications, Inc., is headquartered in Boca Raton, Fla. For more information, visit www.usa.siemens.com/communications

Note: Siemens is a registered trademark of Siemens AG, its subsidiaries or affiliates. All other company, brand, product and service names are trademarks or registered trademarks of their respective holders.

This release contains forward-looking statements based on beliefs of Siemens management. The words "anticipate," "believe," "estimate," "forecast," "expect," "intend," "plan," "should," and "project" are used to identify forward-looking statements. Such statements reflect the company's current views with respect to future events and are subject to risks and uncertainties. Many factors could cause the actual results to be materially different, including, among others, changes in general economic and business conditions, changes in currency exchange rates and interest rates, introduction of competing products, lack of acceptance of new products or services and changes in business strategy. Actual results may vary materially from those projected here. Siemens does not intend or assume any obligation to update these forward-looking statements.

For additional information contact:
Siemens Communications, Inc.
Barry Lawrence
703-262-2020
barry.lawrence@siemens.com

Calix
Jeannette Bitz
510-748-8200 x207
jbitz@engagepr.com