XO Communications expands wholesale VoIP services with Acme Packet

BURLINGTON, MA, FEBRUARY 7, 2008—Acme Packet® (NASDAQ: APKT), the leader in session border control solutions, today announced that XO Communications has expanded its installed base of Acme Packet Net-Net® session border controllers (SBCs) to support its wholesale service provider VoIP customers.

Launched in 2005, XO’s wholesale VoIP services enable sevice providers to originate and terminate customer voice calls throughout the United States with a single connection to the XO IP network. This service helps XO’s service provider customers reduce costs in markets where they offer service, enter new markets more quickly and more efficiently manage voice traffic on a nationwide basis.

Acme Packet’s Net-Net SBCs are used by XO Communications to facilitate interoperability between peering networks and to provide protection of XO’s VoIP infrastructure. Acme Packet’s Net-SAFE security architecture provides denial of service attack protection, topology hiding and access control to protect XO’s network. Acme Packet SBCs also enable XO Communications to maximize its service reach and revenue potential by normalizing signaling protocols at the interconnect border. Acme Packet’s policy-based call admission control features ensure high-quality voice calls while protecting XO’s network from overloads.

“The Acme Packet solution delivers on our requirements for a secure and scalable wholesale VoIP offering,” said Bryan Burns, vice president of network planning at XO Communications. “We first deployed the service in 2005, and we have continued to deploy additional Acme Packet equipment ever since because of Acme Packet’s commitment to customer service and XO’s growing demand for SIP connectivity.”

“As an early provider of SIP-based services, XO is very experienced in delivering the critical aspects of carrier-class wholesale offerings,” commented Seamus Hourihan, vice president of marketing and product management, Acme Packet. “XO continues to invest in our session border control solutions to maximize its service reach without compromising security.”

About Acme Packet
Acme Packet, Inc. (NASDAQ: APKT), the leader in session border control solutions, enables the delivery of trusted, first class interactive communications—voice, video and multimedia sessions—and data services across IP network borders. Our Net-Net family of session border controllers and multiservice security gateways supports multiple applications in service provider, large enterprise and contact center networks—from VoIP trunking to hosted enterprise and residential services to fixed-mobile convergence. They satisfy critical security, service assurance and regulatory requirements in wireline, cable and wireless networks; and support multiple protocols—SIP, H.323, MGCP/NCS and H.248—and multiple border points—interconnect, access and data center. Our products have been selected by over 465 customers in 85 countries, including 24 of the top 25, and 79 of the top 100 service providers in the world. For more information, contact us at +1 781.328.4400, or visit www.acmepacket.com [1].

About XO Communications
XO Communications, a subsidiary of XO Holdings, Inc. (OTCBB: XOHO), is a leading provider of 21st century communications services for businesses and communications services providers, including 50 percent of the Fortune 500 and leading cable companies, carriers, content providers, and mobile operators. Utilizing its unique and powerful nationwide IP network and extensive local metro networks and broadband wireless facilities, XO offers customers a broad range of managed voice, data and IP services in 75 metropolitan markets across the United States. For more information, visit www.xo.com [2].

Media/analyst contact:
Investor relations:

Andrea Joest
Brian Norris

Connect2 Communications
Acme Packet

+ 919-554-3532 ext 110
+1 781-328-4790

andrea@connect2comm.com [3]
bnorris@acmepacket.com [4]