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

At the end of 2016, BT Wholesale boldly announced that by 2020 customers will no longer be able to purchase ISDN and PSTN circuits. As of 2025, the aim is that these circuits will be switched off and that customers will move over to VoIP 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. Whereas once ISDN was the go to option for video-conferencing and fast internet connections, it has now been overtaken by more recent innovations – like fibre broadband.

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 (a decade) to make the switch.

What should your business do?

  1. Start exploring VoIP

Firstly, start looking into VoIP systems. Read about the benefits and additional features of VoIP, hosted and SIP technologies and start getting a bit more comfortable with all the terminology. 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). Although there is no rush to make the switch, 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. Network Telecom 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

Keep calm! Whether or not BT stick to the 2025 date, 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

At Network Telecom, 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 01952 221 327 or email



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Network Telecom (UK) Ltd
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