Switched telecoms

Switched telecoms systems are older voice telecoms systems that are sometimes also called public switched telecoms network (PSTN) and plain old telecoms service (POTS). They are being replaced by internet protocol (IP) networks.

Switched telecoms systems use electronic switching systems to connect telephone calls. Historically, the first telecoms networks actually used mechanical switches. Although the technology has advanced, the underlying architecture has not and PSTN works in much the same way it always did.

Leased lines provide a constant connection between fixed points, they are therefore not switched because there is no need for switching.

Both leased lines and switched telecoms are now being replaced by internet protocol (IP). This technology, which was originally developed for the internet, carries data divided into packets, which are routed to their destinations by software rather than electronic switching.

Most telecoms companies moving to pure IP networks, so that even customers who subscribe to what appear to be PSTN networks will actually have their calls carried (in part) by IP networks. This allows telecoms companies to make savings by replacing separate voice (PSTN) and data networks with a single IP network.

The emergence of consumer VOIP technologies means that calls can now be carried over an IP network end-to-end.