Blog | How will the ISDN and PSTN switch off impact your business?

How will the ISDN and PSTN switch off impact your business?

Towards the end of 2017, Openreach announced that they would be switching off the traditional Public Switched Telephone Network (PSTN) and withdrawing all analogue products that rely on it by 2025. All businesses should be aware of this termination date and put a contingency plan in place by 2023 when the supply of new analogue voice and broadband services comes to a halt.

Why is the ISDN and PSTN switch off happening?

Businesses all across the UK have been using analogue and ISDN services for decades. However, they are aging technologies and are becoming much more expensive and difficult to maintain. For this reason, Openreach have made the decision to switch off the PSTN network and move everyone over to an all-IP network instead.

Organisations who have not arranged for an alternative solution to replace their end of life (EOL) services before the switch off will experience major disruption to their business. Openreach announced 297 priority exchanges that will be listed as ‘stop sell’ by April 2022, many of which are already affected. For this reason, we are advising all UK businesses, including existing DuoCall customers, to review their current telephony and connectivity solutions sooner rather than later.

Free review of your business’ communications

We care about the future of your business’ communications, and with the 2025 switch off looming, we want to make sure you avoid any unnecessary disruption to your services. That’s why we’re offering a free, no obligation review of your existing setup. Our team will help you prepare for the switch off and recommend a future proof solution that works for your business, should you need one. It’s better to be safe than sorry!

Free consultation

What services will reach EOL in 2025?

The following services will be switched off by 2025:

  • WLR3 analogue
  • ISDN2
  • ISDN30
  • Narrowband Line Share
  • ADSL broadband
  • FTTC broadband
  • G.Fast broadband

A timeline of the PSTN switch off

What does stop sell mean?

Exchange areas are listed as ‘stop sell’ by Openreach when 75% of that area is fully fibre-enabled. Businesses and homeowners in stop sell areas are no longer able to purchase new PSTN/ISDN phone lines or analogue broadband solution such as Fibre-to-the-Cabinet (FTTC). They must purchase a data-only solution if they wish to upgrade instead.

What is the PSTN network?

PSTN stands for Public Switched Telephone Network.

This network of telephony services has been in place since the 1800s. It uses underground copper wires to deliver a connection to businesses and households all over the UK. For this reason, the switch off will affect everyone in the country who is currently using analogue voice and broadband services.

With technology developing constantly, it’s now time to turn off the PSTN network and replace it with an all-IP alternative.

PSTN phones are often referred to as landlines, Plain Old Telephone Service (POTS), and fixed-line telephones.

What are ISDN lines?

ISDN stands for Integrated Services Digital Network.

BT rolled out ISDN services in 1987 as a replacement for traditional analogue lines. ISDN lines allowed businesses to make voice calls over data networks, utilise video conferencing, send and receive faxes, and print from your own computer. It delivered much better sound quality too.

At the time of the ISDN roll out, ISDN services offered much more flexibility and functionality for telephone system users, but technology has once again moved on. ISDN services are now limited by the copper infrastructure they are transmitted over. For this reason, all ISDN services will be included in the PSTN switch off in 2025.

What will replace ISDN and PSTN services?

Traditional business communications systems deliver voice with connectivity layered over-the-top (OTT). However, this is very complicated and expensive to maintain. For this reason, the traditional copper network will be replaced by IP services. These 21st century solutions are much more appropriate for modern-day businesses as they don’t rely on a 20th century copper network to function, just an internet connection.

If your business currently owns an on-premise IP PBX phone system, you will need to replace your ISDN services with SIP trunking, a public IP telephony service based on session initiation protocol lines. SIP trunks allow you to make and receive calls over a data connection with much more flexibility than ISDN.

Although SIP trunks will enable your business to continue operating after the switch off in 2025, hosted telephony, or VoIP (Voice over IP), will be the solution of choice for most businesses looking to replace their outgoing PSTN or ISDN services.

Benefits of hosted telephony

Hosted phone systems enable you to make and receive voice and video calls via an internet connection. This means that they don’t rely on the PSTN or ISDN lines whatsoever.

Our simple guide outlines everything you need to consider when deciding on the right phone system for your business. If hosted telephony sounds like a solution that could benefit your business, take a look!

Read our guide

What will replace analogue broadband solutions?

If your business currently utilises analogue internet connectivity, you will need to install a data-only connection before the switch off in 2025. Alternative solutions include:

  • Leased Line
  • Fibre-to-the-Premises (FTTP)
  • EoFTTC
  • EFM

If you know that your business currently uses an outgoing ADSL, FTTC or G.Fast broadband connection and you don’t know which replacement solution is most suitable for you, let us know. We’d be more than happy to point you in the right direction.

What other services will be affected by the analogue switch off?

All systems that rely on analogue voice and broadband services will be affected by the major switch off. This could include services such as security systems, fire alarms, payment terminals, monitoring equipment and telecare devices etc.

If you are concerned about how futureproof your systems are, you should talk to the system manufacturers to find out whether their services are compatible with the new IP technology standards.

Need more information about the ISDN and PSTN switch off?

If you would like more information about the 2025 analogue switch off, we’d be more than happy to help. Contact our team on 0333 313 5000 or send us an email to

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