Soft switches provide an interface between the PSTN, PBXs and IP telephony, allowing traditional carriers to take advantage of the flexibility of IP without giving up networks and hardware in which they've invested billions over past decades.
In simple terms, a soft switch is an application which sends incoming calls through a media gateway rather than the standard class five switches that telcos use.
The gateway converts the call into IP packets or another packet-based format and routes it to a gateway near its destination, which changes it back to a standard phone call.
The main virtue of using soft switch technology is that it allows traditional telcos to be more flexible and much faster at introducing new services and can even enable users to customise services to their individual needs.
Server-based, soft switching operates to open standards, unlike the proprietary operating systems and application software that drive PSTN switches.
A customer could, with the right expertise, modify a telco's service range to suit its own needs using software and telcos themselves could also pick and choose between hardware and software from multiple vendors to ensure they offer the service range they want and easily add new services.
Calling card applications, unified messaging and 0800 numbers are some of the applications that can be offered using soft switching and done so more cheaply and faster than by getting a traditional telco equipment supplier to add them to a class five switch.
The open nature of soft switching also means it can be integrated with existing legacy databases, thus enabling data so stored to be accessed through new soft switch-generated services.