PDF of this tutorialDefinition
Softswitch is the generic name for a new approach to telephony switching that has the potential to address all the shortcomings of traditional local-exchange switches. The softswitch is where all the service intelligence resides for the delivery of local telephone services. Softswitch technology solutions can lower the cost of local-exchange switching, present the means to create differentiated local telephony services, and ease the migration of networks to support packet voice end-to-end.
Packetized voice involves the digitizing, compressing, and dividing of voice into packets. These packets can then be sent from the sender, via various routes, to the receiver, whereupon they are reassembled.
Overview
This tutorial is intended to help network planners and technologists who are responsible for the planning and design of local broadband and voice access networks. The focus is on softswitch technology and packet voice and the roles they play in the migration toward fully converged local networking. Broader questions of network evolution are covered as well.
The unbundling of network elements, a key aspect of the deregulation of telecom networks that is now taking place all around the world, has finally opened up the local telephone services market to competition. Competitive service providers have been able to enter the market and win a substantial share, particularly for medium-sized business customers, those with 100 employees or more.
Recently, packet voice solutions that exploit digital subscriber line (DSL) transmission technology have dramatically improved the business model for deploying voice over unbundled loops. Voice-over–DSL (VoDSL) solutions are enabling competitive service providers for the first time to address profitably small-business and upscale residential customers, while incumbents plan to exploit VoDSL both as a defensive strategy and to address copper pair shortage problems.
VoDSL technology undoubtedly provides a major boost to competition in local telephony markets by greatly reducing the cost of local access. But this use of packet voice within the access network has done nothing to change the switching infrastructure for local telephony, which continues to be based on traditional circuit-based local-exchange switches. The high cost and large scale of this equipment is a major deterrent to any service provider that wishes to enter new markets, particularly in second- and third-tier cities. Furthermore, service providers are limited by the capabilities of the switch to offer voice services and calling features that are identical to those provided by the incumbent. As a result, service providers are forced to compete almost solely on price, and this is unlikely to provide a sound basis for long-term business viability.
A technology known as "local-exchange softswitch" has the potential to change radically the landscape of local-exchange switching. Properly applied in the local network environment, the local-exchange softswitch can deliver an irresistible combination of dramatically lower equipment cost and greatly enhanced calling feature functionality. Local-exchange softswitch should promote the graceful evolution of access networks from circuit-based to packet-based—a key step in the migration to end-to-end packet voice—thereby revolutionizing local telephone services.
