Whats happening to ISDN phone lines ?

The ISDN switch off is due to take place in 2025, and BT will stop accepting amendments and new orders in 2020. The BT ISDN switch off could affect many businesses in the near future, especially those unaware of BT phasing out ISDN and looking to invest in or upgrade their current business telephone system. [separator]Does this fact fill you with dread?                       Not sure what the alternative is?                          Don’t panic, it will all be okay.           We’ve taken the ISDN geeky stuff and simplified it below –

What is ISDN?

ISDN is a type of telephone connection that businesses use. It stands for Integrated Services Digital Network. They’re the step up from your normal home landline connection in that they offer multiple calls to one number, video conferencing and other business requirements.  It comes in two formats, ISDN2E (a pair of lines) and ISDN30 with up to 30 channels. It was first offered out to businesses in 1980 and offered the best technology for phone systems at the time.


Why the ISDN Switch Off?

The short answer is that they are old fashioned legacy technologies with associated maintenance costs and drawbacks. PSTN is the traditional telephone line network which carries analogue voice data over copper lines. This technology (although vastly improved upon over the years) is basically the same in principle and design as the early telephone networks of the late 1800’s. . For the technology and services at the time, it served its purpose very well and continued to do so for many years.

Now we’re well into the 21st century, technology has moved on and old telephone solutions are lagging behind the alternatives in an increasingly fast paced digital world. Just like the technology in our mobile phones is improved and enhanced regularly, so business phone system technology changes

The BT ISDN switch off marks the next evolution of telecommunications technology.

What Next ?

Now ISDN has had it’s hayday, there is now a much simpler, and cheaper alternative.  That alternative is VoIP or Hosted PBX,  – cloud based phone systems – think of phone lines over the internet rather than the copper cables that ISDN connections use.

. You could look at cloud based Hosted PBX as the newer model of ISDN with one big difference.

Hosted Voice phone systems are actually cheaper than ISDN, and that’s one of the main reasons for the ISDN switch off.


Here’s a quick overview of the main business benefits for using hosted VoIP:

It’s very affordable/cost effective

  • There’s no need for masses of on site equipment, you only pay for as many users as you need and calls are made through internet lines.

Easy setup & maintenance

  • Because there is so little on site equipment, setting up and maintaining the system is a much simpler job than with a traditional telephone system.


  • The flexible nature of the technology allows you to easily add and remove users as you need. Physical location doesn’t matter, anywhere you’ve got an internet connection, you can have a number.

see our blog Benefits of a Hosted System   


What can you do to prepare?

The first thing you can do to get prepared is to find out when your current ISDN contract expires.

2025 may seem like a long way off but it will come sooner than you think.

Rather than signing up for another year with your traditional phone system, why not start looking into internet phone systems now and get ahead of the curve?

Go to a few VoIP providers and get some quotes…….and call Trio Telecom today on 01727 221303