Softswitch Characteristics

A softswitch is a high-availability computing platform that houses software to control multimedia traffic over an integrated telecom network and mediates the signaling between packet and circuit-switched networks (i.e., between the IP-based and the legacy TDM domains). Softswitches may be considered software-based replacements for class 5 (local exchange) and class 4 (toll exchange) central offices.

These systems promise an excellent opportunity for service providers to deliver new, innovative broadband services, while reducing equipment and personnel costs by up to 50%, compared with conventional, digital CO systems. The legacy switches, made by the eight major telecommunication equipment manufacturers, are highly proprietary in nature.

A softswitch should reside in an extremely reliable (i.e., extensively redundant), industry-grade, rack-mounted server in a secure network data center. Ample power supply and network access backup capabilities are also essential. Softswitches work in close conjunction with modular media gateways and, partly because of the physical separation of control and packet-switching functions, can be scaled in capacity to meet quickly changing traffic patterns more easily than with older circuit switches.

A significant feature of softswitches is the facility for a system administrator to install and manage all the telecom services of the switch through a Web portal. In this users are offered a much better way to control their own network, such as ordering new services, click-to-call on any numbers, modifying call forwarding, and customizing individual telephone sets (whether real or virtual). For these reasons, managing telecom services will become much easier than it has been with on-premise PBXs or off-site Centrex services. With a softswitch it should be just as simple to administer video-conference services as voice calls, which will be a big improvement over legacy class 5 CO capabilities. Some of these softswitch entities are illustrated in Figure 1te.



Figure 1 :Softswitch configuration.
Carrier grade softswitch products have been on the market since late 2001 from established manufacturers, such as Nortel Networks and Siemens, as well as recently started companies including Sonus and Tanqua Systems. Most of the newer companies in this line of business belong to the Softswitch Consortium.

The early applications of softswitches were for off-loading Internet traffic, from more expensive and busy CO systems, primarily with DSL on the line side and IP or ATM on the trunk side. Going forward, the role of softswitches will be much more to replace conventional central office systems and to deliver multimedia IP-Centrex services. Softswitch availability is the key for the development of hosted telephony services by the competitive service providing companies and for the capability of putting all an organization's voice, video, and data traffic onto a single network.