The end of ISDN is approaching, what should you do?

Monday, 19th July 2021
Did you know the UK is set to discontinue traditional ISDN phone lines by 2025? As of 2025, ISDN and PSTN circuits will be switched off and customers will move over to Cloud Telephone Systems. But, what should you do in the meantime and what will these changes mean for your business?

What are PSTN and ISDN?

Public Switched Telephone Network (PSTN) and Integrated Services Digital Network (ISDN) are the circuits that most of us currently use to communicate over the phone. PSTN is an older technology (operating using the same principles as the first ever public phone network) which sees analogue voice data flowing through circuit-switched copper phone lines.

ISDN however, is more recent, using technology from the late 1980s and delivering both voice and data services over digital lines at the same time. ISDN was once the go-to option, but now companies require digitally integrated solutions that can handle the pressure of high-bandwidth activities such as video conferencing.

What will replace ISDN?

In short, PSTN and ISDN circuits will be replaced by VoIP (Voice over Internet Protocol) systems. To make the switch, your business can either opt for a hosted system or talk to us about upgrading your existing phone system so that you can connect it to your broadband connection.

With a hosted system, your calls will be delivered via the internet and there will be no need for telephone system hardware (other than handsets), dedicated telephone lines or specialised engineers. With a hosted voice system, you’ll be able to enjoy cheaper call rates, free site-to-site calls, the ability to pick up calls across multiple devices and the facility to add users quickly and easily while benefiting from HD call quality and recording. Your business phone system will become more scalable and flexible to your company’s needs.

If you choose to keep an on-premises business phone system, you will be able to enjoy all the benefits of VoIP, such as scalability, HD quality calls and cost savings. Instead of PSTN or ISDN circuits, your business will need SIP Trunks – virtual telephone lines that create a phone line over your internet connection. SIP trunks are great for flexible working, have built-in disaster recovery and can be scaled up or down without the need for additional physical line installation.

Why are BT going to stop selling ISDN?

Maintaining legacy networks is extremely expensive and BT need to move with the fast pace of communications technology, while still giving customers enough time to make the switch.

What should your business do before ISDN Shut-down?
  1. Start exploring VoIP

Start looking into VoIP systems. Check that you have a good internet connection that will be able to deliver VoIP services and see if your business telephone system already supports VoIP (many new office phone systems do).

You may want to check the terms of your contracts, see if you can make cost savings by switching early and work out when will be a good time for your business to make the change. Enreach operate a scrappage scheme to help you upgrade so it is worth speaking to your provider and talking through your options.

  1. Don’t panic

There is a lot of progress that needs to be made for the switch off to become a reality. The UK will see a full fibre rollout, increasing our connectivity, and BT will ensure that the 33.2 million fixed landlines in the country are catered for. As a business, the best option is to familiarise yourself with the new technology and speak to your business telecoms provider about how to modernise your system.

  1. Get in touch

Here at Enreach, our team of expert advisors are always on hand to talk to both new and existing customers about the move away from ISDN and how we can help you make the switch. We are more than happy to talk through any questions or concerns that you may have. Just call 0333 251 3659, talk to us instantly on our chat bot or email

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Enreach UK Ltd, Communications House, Hadley Park, Telford TF1 6QJ
Call us: 0800 097 6543 Email:

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