What Is PSTN? The Public Switched Telephone Network Explained

PSTN stands for Public Switched Telephone Network. It's the traditional copper-wire phone network that has carried landline calls for decades.

How PSTN Works

PSTN uses physical phone lines (copper) to connect calls. When you dial a number, the call is routed through local exchanges and long-distance networks until it reaches the destination.

The UK PSTN Switch-Off

BT Openreach is switching off the PSTN by December 2025. All landlines will move to digital (IP) technology. Businesses need to migrate to VoIP or similar solutions before the deadline.

PSTN vs VoIP

VoIP sends calls over the internet instead of copper lines. It's more flexible, often cheaper, and supports features like video and integration with business software. Migrating from PSTN to VoIP is the recommended path for most businesses.