Softswitch Fever: The Bedrock for Next-Gen Services - Technology Information

Telecommunications, Jan, 2000 by Doug Allen

Level 3 got into the softswitch game in late 1998 with its Managed Modem service, which currently operates modem bands and local exchange carrier trunking on behalf of ISP customers in 20 metropolitan and regional areas. Based on an in-house Viper softswitch, the service has grown to roughly 2 million calls per day according to Ike Elliott, Level 3's senior director for voice network engineering. "We believe we have already realized operating efficiencies and capital cost savings with this service, due to the softswitch architecture. The quality of service (QoS) as measured by call success rates has improved steadily since the service was launched, to the point where measurements by both us and our customers are showing that our quality is higher than any other modem service supplier." Level 3 has agreed to purchase at least $250 million worth of Lucent softswitches and planned to launch its softswitch-based VoIP by the end of '99.

Global Crossing, via its Frontier acquisition, also plans to use Lucent's softswitch with the Sonus Networks GSX9000 gateway (See Figure 1). Clearly, Lucent's voice expertise and built-in library of more than 3000 customized services has been decisive so far, though a number of start-ups have scored heavily with greenfield CLECs/ICPs. To grow the market, service providers want to be sure the softswitch can originate calls using one signaling protocol and terminate them using another, supporting at least SS7, ISUP, SIP, H.323 and MGCP. Products must be interoperable with "as many devices as possible," said Elliott, "especially VoIP gateways, network access servers, integrated access devices (IADs) and groomers."

"One way of looking at this is how 'plug-compatible' these switches will be with prior generations." said Robert Kelley, director of innovation voice and multimedia at Rhythms NetConnections. Another way is to consider how these switches will provide comparable, but not necessarily compatible, features. Also, what types of legacy interfaces will be supported, such as GR303 for lines, or various trunking interfaces, or signaling interfaces a la SS7?"

Where to Deploy

One of the softswitch's advantages is that it can be distributed throughout the network or centralized, as the case may warrant, making it appropriate for a variety of telco missions. No one method will fit all, but just about every provider can benefit from its flexibility. For large networks, multiple softswitches can be distributed to manage different domains or zones. Services can also be accessed from the platform locally or from other regions. Smaller networks may require just two softswitches (for redundancy). Additional softswitches may be added to keep latency low when customer demands ramp up. This approach also allows carriers to use softswitches in new regions when building out their networks without having to buy circuit switches.

"From a network deployment perspective, the main question may be: Are there lots of smaller softswitches distributed to the network edge, or are there fewer and larger switches in major metro area network centers, or even fewer softswitches in large data centers connected to very high-speed fiber backbones?" Kelley said. The granularity and scalability approaches may differ among vendors. "IP-based approaches lend themselves to having some switches in private enterprise networks and interoperating with service provider networks to create cost-effective private voice and data network solutions," he said.