UK PSTN Switch-Off: What Will Change and How to Prepare?

The PSTN switch-off is the retirement of the traditional Public Switched Telephone Network used to deliver analogue landline calls. Calls that previously travelled through the old network will instead use digital technology, such as VoIP (Voice over Internet Protocol), Digital Voice, or another All-IP service delivered through an internet connection.

In the UK, PSTN switch-off is only one part of the change. BT (British Telecommunications) Group and Openreach are also withdrawing ISDN, ADSL, and related analogue services that form part of its Wholesale Line Rental network. If you use any of these services, you will soon need to move to a compatible IP-based alternative.

The UK PSTN switch-off is scheduled for 31 January 2027. By this date, BT Group plans to retire its traditional telephone network. However, the switch-off is not a sudden change. The telecom industry first announced the transition in 2017, and Openreach has introduced it in phases.

The PSTN has carried UK landline calls for decades, but the network is showing its age. It is becoming harder to maintain because many manufacturers no longer make the specialist parts needed to repair it. Moreover, copper-based services are more vulnerable to faults and outages.

In other words, the industry is spending more time keeping an ageing network running with increasingly limited parts and expertise. Replacing it now is more practical than waiting for reliability to decline further.

The switch-off may affect more than your business phone calls. Many alarms, payment systems and other devices still use analogue lines in the background, even when they do not look like telephone equipment.

Check whether any of these services are connected to your current line:

• Intruder and fire alarms: Some monitored alarm systems use PSTN lines to contact a monitoring centre and may need an IP or mobile connection.
• PDQ and card payment machines: Older terminals that dial through a phone line may need to be replaced with an internet- or mobile-connected model.
• Fax machines: Traditional fax machines depend on analogue lines, so you may need an online fax or fax-over-IP service.
• Door-entry systems: Intercoms and access systems that call a landline number may require an IP-compatible replacement.

The PSTN will be replaced by digital phone services that carry your calls over a broadband or internet connection. The two main options are a provider-managed digital voice service and a VoIP business phone system.

With a provider-managed digital voice service, your provider moves your existing landline onto its digital network.

For example, BT customers moving to Digital Voice can connect their handset to the phone port on the back of their hub. By doing so, you can keep using the same phone for calls, but the service runs through the broadband connection instead of the old wall socket.

Likewise, Sky offers similar Internet Calls through eligible broadband packages, while TalkTalk provides Digital Voice through a compatible router or adapter.

For your business, a VoIP phone system offers a more flexible replacement. Your phone numbers, users and calls are managed through an online platform rather than a traditional phone line or on-site system.

You and your team can make and receive business calls from desk phones, computers, mobiles or web browsers, whether you are in the office or working elsewhere.

Moving from a traditional phone line to VoIP is usually straightforward, but you should plan the change before your existing service is withdrawn.

List the phone numbers, extensions and devices your business uses.

VoIP carries your calls over the internet, so your connection needs to be stable enough to support your team’s call volume. You should also consider a backup connection or mobile service in case your main broadband goes down.

Compare providers based on your number requirements, team size, supported devices, pricing and customer support. Make sure the service can support how your team works now and as your business grows.

You can get an online phone number or port your current business phone numbers to the new provider. Start this process before cancelling your existing service, as closing the line too early could put your numbers at risk.

Add your users, connect your chosen devices and test both incoming and outgoing calls. Check call quality, number display and access across desktops, mobiles and browsers before completing the switch.

Once everything works correctly, you can move your team fully to the new system and cancel any legacy services you no longer need.

Waiting until January 2027 leaves little room to deal with unexpected problems. Your provider could also migrate your service earlier, so your existing lines may change before the final switch-off date.

Move as early as possible, so you get the time to check every service connected to your phone lines, transfer your business numbers and test your new system while the old one is still active.

Most importantly, you can complete the change at a time that suits your business. That means less pressure on your team and a lower risk of rushed installations, missed calls or service disruption close to the deadline.