Service providers’ traffic is increasingly moving from voice to data, and the present TDM switches are unable to cope up with emerging data applications. So, vendors are focusing more on next-generation switches as they are designed according to data requirements of the service providers. In India, things are moving slowly towards next-generation switches. There have been a few pilot deployments and one can expect large-scale deployment very soon.

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Most traditional TDM switches are costly and occupy a lot of space whereas softswitches come at a fraction of that cost and space. Service providers are hence increasingly opting for softswitches for voice-based applications and next generation switches for 3rd generation network.

Soft switch is a software-based switching platform as opposed to a hardware-based switching platform. They are based on open systems whereas TDM systems are based on proprietary standards. Softswitch is a generic term for any open-application program interface software used to bridge a public-switched telephone network and VoIP by separating the call-control functions of a phone call from the transport layer. Simply put, Softswitch is the concept of separating the network hardware from network software. In traditional circuit-switched networks, hardware and software are not independent. Circuit-switched networks rely on dedicated facilities for inter-connection and are designed primarily for voice communications. More efficient packet-based networks use Internet Protocol (IP) to efficiently route voice and data over diverse routes and shared facilities.

Softswitch, media gateway controller, call agent, and gatekeeper can be clubbed together to perform the functions that are coming to be called softswitches. Gatekeeper is the ancestor term, derived from VoIP systems in which gateways converted the voice and signaling from analog PSTN and SS7 to IP packets. The gatekeeper controlled one or more gateways, guiding the setup and teardown of voice circuits between the two kinds of networks. Media gateway controller is an elaboration of gatekeeper, growing out of the first efforts to standardize the control of media gateways using a protocol called media gateway control protocol (MGCP).

The functions of a softswitch fall under four different layers: applications and features; service-creation environment; call control or a call agent; and protocol mediation, enabling devices, such as gateways, using different protocols to communicate. Feature servers are the newcomers to the softswitch landscape, emerging as a repository for applications and databases that can be used to deliver services above and beyond the simplest call control. But the term is deceiving, because a feature server is not a discrete entity, but rather a number of servers spread out over one or more networks that can be accessed to deliver services.

An emerging issue is whether features have to be on the softswitch itself or relegated to a feature server. In the PC model there are operating systems and applications, and they are clearly separated. However, an operating system often includes basic application functions, such as the ability to display pictures and play audio. Likewise, on a softswitch too, there are certain applications such as basic call routing, where it is difficult to segregate them from the call agent because of policy issues.

The future benefit of Softswitches will be dictated by the extent to which network control and service logic also migrate away from the switch. Distributing functionality means that switches will be simpler, more efficient, and cheaper. Switches will be able to focus on switching, allowing other components to provide network control and service logic. Distributed service logic means that application development will not be constrained to centralized creation, control, and service delivery. Instead, services can be created and deployed at various places through an extended network.