What is Softswitch?

The term, which we are considering here, is typically used for any separating device, but we are looking from the perspective of telephone calls where the term Softswitch intended to calls from IP to IP. Some phrases like “access server” or “media-gateway” which already makes us familiar with phone calls by land lines (cable-system). Taking into account the practical application of such systems as Softswitch such telephone calls through the Internet, as from Skype to Skype, where are used such telephone commutators, in which the connection provides somewhere in the middle (between the caller and receiver). Speaking about the significant difference between the familiar access server systems, where a call from a landline or mobile phone transforms into the stream of Internet network, and then the same device is converted back into ISDN digital or analog/PSTN format, and finally the call comes to your destination.

Normal use of commutator is connection of the switching channels in network and packages, in general, one hardware components could serve as a switch of logistics operations and a switch of fabric, but in our fashionable technologies time prefer to separate these two functions into a Call Agent and a Media Gateway.

Most of the functions such as Turnover of accounts, the direction of the call, the call service and so on, are controlled by the Call Agent. It also provides a functional solution to all problems associated with the distribution of telephone calls. It can also monitor calls in the Media-Gateway different areas (a TCP/IP link network), depending on geographic location.

Complete the process of connections data and sound transmission from the beginning to the end of the route organizing Media Gateway, and it’s summarizing all digital streams into a single entity in the call. It may have an interface as in traditional networks like PSTN networks, such as DS1 or DS3 ports (E1 or STM1 in the case of non-US networks); and in more modern connection ports to ATM and IP networks, and last one - Ethernet for VoIP connecting calls. Call Agent will organize connection between this various types of interfaces,  so that the result of this process would be understandable for each user.

Central office, which is owned by the telephone company and in which all devices - switches regulates the network PSTN calls to other telecommunications companies. Multiple access devices connected via Media Gateway from the ordinary analogue telephone adapter (ATA) into many connections through IAD or PBX.

Telecomunication companies usually place the larger Access devices in premises they own near the users that use their services. IAD can be connected by every end user via copper cables. Companies usually choose devices of medium-size and PBX’s in their own offices while private users usually choose devices of single-line.

At the beginning of the millennium when referring to IP Multimedia Subsystem (or IMS) the name Media Gateway Controller (MGC) device is used more often rather than Softswitch device. When referring to Softswitch it is usually named as AGCF (Access Gateway Control Function).