The PSTN switch off

Jun 5, 2023 | Fire Safety, Intruder Alarms, Security Systems

How will the PSTN switch off effect your intruder alarm and what do you need to do to ensure your alarm can still be monitored is outlined in this blog post.

What is PSTN?

The Public Switched Telephone Network (PSTN) is the UK’s national infrastructure, it underpins traditional phonelines, ISDN, and ADSL2. This telecommunications infrastructure network was built to replace the existing telephony from the days of Alexander Bell. It’s an analogue network that operates via what are now referred to as landlines. Until recent times it was the default system for homes and businesses.

PSTN due to be switched off completely by 2025, over the last few years there has been a real drive to get businesses moved over to VoIP. This is also called IP telephony, which is the current technology in place for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks.

Intruder alarms and PSTN

Many traditional intruder alarm systems in the UK use PSTN lines for communication with monitoring centres or for sending alerts. With PSTN due to be switched off, systems need to be upgraded or replaced with alternative communication methods of internet protocol (IP) or broadband-based alarm systems.

These newer systems use the internet for communication and can be more reliable and versatile than PSTN-based systems. They use Voice over IP (VoIP) or cellular connections to transmit alarm signals to monitoring centres. If your alarm is still connected to the PSTN network, it needs to be updated for your monitoring to still be conducted.

If you don’t upgrade your alarm’s PTSN line, then you won’t be able to utilise the monitoring services with your provider. It’s really that simple.

It doesn’t necessarily mean that you’ll need a completely new alarm*, as it’s the telephone line that is the issue for any security system using a professional monitoring service.

*That might depend on the age of your security system, please seek specialist advice on this.

Don’t forget fire alarms!

If you have monitoring on your fire detection systems then it’s a good idea to check whether these are the new digitalised communications or still on a PTSN line. The same applies as for your intruder alarm, if it’s a PTSN line then you’ll need to switch soon to ensure monitoring can still be completed by your provider.

Make a move

Don’t be caught out by the date, 2025 is the official PTSN line switch off by BT but they are undertaking a phased approach to the closure so it might be better to check your area status sooner rather than later!

If you need to understand whether your fire and security systems are using up to date communications our team are happy to help, drop us an email to or call us on 0800 2545645.