Short for software switch, a softswitch is an API that is used to bridge a traditional PSTN and VoIP by linking PSTN to IP networks and managing traffic that contains a mixture of voice, fax, data and video. Softswitches are able to process the signaling for all types of packet protocols. Softswitch is a software-based switching platform, which is opposed to traditional hardware-based switching center technology. Softswitches also are based on open systems, another difference between them and traditional proprietary hardware switching systems.
Softswitch is also called media gateway controller, call agent and gatekeeper.