The PSTN Switch Off

In 2025, BT is preparing to phase out the Public Switched Telephone Network (PSTN) and the Integrated Services Digital Network (ISDN). These networks will be shut down for good and will be replaced with Voice over Internet Protocol (VoIP).


What does this mean for my business?


This means that for any fire & security equipment that uses the old signalling devices will effectively be redundant from the switch off. That’s why it’s important to ensure that your business becomes future proofed ready for this changeover.

  • What is PSTN & ISDN
  • What does this mean for my fire and security?

PSTN is what we all know as the traditional phone line, transporting analogue voice data over copper phone lines.


ISDN is the original high-speed internet service and is a telephone-based network service which transmits data and phone conversations simultaneously over standard telephone cables.

It is estimated that around 4 million fire and security systems which communicate to alarm receiving centre’s (ARCs) use the PSTN network. If you have a fire, intruder, access control or CCTV system that uses the PSTN network, it’s evident that these changes will impact you. To outline this, if you don’t upgrade your signalling device within your fire and security system to one that doesn’t depend on the PSTN network, then your monitored solution will no longer be effective.

Schedule A Call Back With Our Team

Receive a FREE Upgrade & Transfer To Us with a FREE Unit & FREE Engineer Visit!

Contact our team today to find out more about how Alert Fire and Security can help your business prepare for the PSTN Switch Off.