What is PSTN (Public Switched Telephone Network)?

The PSTN (Public Switched Telephone Network) is the traditional circuit-switched analogue telephone network that has carried UK voice calls for over a century.

BT Openreach is retiring the UK PSTN on 31 January 2027. Every analogue line, ISDN circuit and WLR2 product stops working that day, which is why UK businesses are migrating to VoIP.

Also searched as: public switched telephone network, analogue phone network.