The Big PSTN Switch Off

What are the facts you need to know?

Change is coming to UK phone and broadband with millions of older lines planned to be switched off over the next 3 years to make way for new technology – also known as the big switch off. 

As Openreach rolls out plans to switch off all old phone lines in phases mainly over the next 3 years but with a backstop of 2025 (PSTN and ISDN to those in the know), we look at the impact on alarm installers, and steps they need to take. 

All alarms monitored by Southern Monitoring & Northern Monitoring use a communication device that sends signals between your customer’s panel system and our ARCs. This means that if we’re connected to the device by an old line, we’re going to need to talk to you about taking action so we don’t lose the connection.

What is the big switch off?

To understand the impacts of the big switch off, we need to understand what is happening.

What are PSTN and ISDN?

This definitely falls into the category of ‘things you didn’t know you needed to know’, but understanding the phone lines connecting your customers’ homes or businesses can help you understand the changes coming up and how they might affect you.

The UK’s telephone infrastructure started being built in 1876 and is known as the PSTN (Public Switched Telephone Network). Since then, it has been developed and updated beyond recognition, but at its heart, it is a very old system that isn’t fit for the 21st century. 

Numerous developments have been ‘bolted on’, including the first wave of broadband lines (ISDN, or Integrated Services Digital Networks) operating on the old infrastructure from the 1980’s onward.

The Switch-off

Around 20 years ago, BT announced bold plans to replace the PSTN with their ‘Network for the 21st Century’, a move calculated to save them billions over the years in the maintenance of copper lines and to provide a better performing, more reliable network. 

After decades of work, the end of the PSTN is finally in view, with trials already underway in two areas and rolling out to the next batch of postcodes as early as May 2021.


How does that affect my customers’ alarms?

You may hear about the switch off from your phone provider and your broadband provider but might not have considered that services such as fire alarms and intruder alarms may also be using the same connection.

If you are one of the 31.7 million remaining users of a fixed-line (PSTN or ISDN) you will need to move to an alternative by the time the switch off reaches your area, or risk being left with no connection.

The security risk of your customers’ alarms losing connection during the switch off is a concern for many, but it is one that can be easily avoided by taking the right steps now. A BT study showed that nearly a third of those surveyed were taking a ‘watch and wait’ approach to the switch off, but we believe that taking action now will help you avoid the worry as the switch-off dates approach.

If your customers’ insurance cover or police response relies on alarm connectivity, there is even more reason to move to a more modern signalling device now.

Here at Southern Monitoring & Northern Monitoring we are committed to working with our customers to smoothly transition their customers’ alarms to a new generation device.

How do I know which areas and customers will be affected?

Working with the signalling device manufacturers, we can provide details of which devices in your customers’ premises rely on a PSTN connection. Your customers can also check with their phone and/or internet provider.

The switch-off timeline

The PSTN will be phased out over a period of 5 years starting in December 2020 and finishing in December 2025. The first phase will simply be a ‘stop sell’, meaning that you will no longer be able to buy or switch lines to a PSTN line. After this, providers will be striving to migrate any remaining customers to a modern connection before the December 2025 deadline.

With many millions of lines for providers to migrate, it makes sense to start investigating your own situation now so that you can be in control of your own migration. Both major suppliers of signalling devices have their new generation devices on the market already.

UPDATED February 2021: We now have details from BT Openreach on the exchanges that will be impacted on the following dates:

  • June 2021

  • October 2021

  • January 2022

For SMS and NMS customers we have mapped the locations of your devices against these exchanges and can help you work through the transition – please contact us and we can help you with this exercise.

Why should I check now?

You may need to swap out a lot of devices, and to save time and cost it will make sense to plan this in with preventative maintenance visits; plus you need to review your device strategy and supplier to ensure you move to the right devices. 

Talk to us now so that you have time to consider your options and make an informed decision.

What should I replace my existing device with?

New generation devices have been launched by both of the major suppliers and are available for installation immediately. Both suppliers have teams of advisers who can help, plus of course, you can talk to us at Southern Monitoring and Northern Monitoring. You need to be aware that the device grading structure has changed, plus different devices have different levels of resiliency and feature sets. Your customer may have specific requirements, and so might their insurers. 

Will my customers’ existing alarms still work on their new modern lines?

Any device that relies on a PSTN will stop working and will need to be replaced. It will affect ALL devices that signal through a traditional phone line, plus we know that 2G and 3G services also have a limited life. With that in mind, we strongly recommend that you look at the latest generations of devices that signal through 4G and IP.

What are we doing to help our customers?

Here at Southern Monitoring & Northern Monitoring we are aware that many of our customers will be affected, and have committed to taking as many advance measures as possible to ease the transition.

We have solid relationships with both major suppliers and can supply the whole range of options.

We can provide you with reports showing what systems you have and highlighting which devices will need changing.

You don’t need to make an appointment or book a slot to commission a new signalling device, our admin teams and 24/7/365 operations teams can help with this on-demand.





Steps you can take

1. Understand where the geographical areas you look after are in the rollout plan.

2. Plan your device migration strategy so you know the options available; which devices will cost more and which devices will cost less.

3. Be prepared for your engineers to make the device swap overs and communications you will be having with your customers.

Remember this will impact every signalling device that relies on a PSTN connection and some areas will be affected soon. We are here to help with any questions about your customers’ alarm signalling and migrating to your new-generation devices.

Please do not hesitate to get in touch if you have any questions.


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