BT have announced they will switch off their traditional phone lines (both ISDN and PSTN) from 2025. They will be changing all their business customers over to Internet Protocol (IP) Technology, predominantly Voice over Internet Protocol (VoIP). This will enable them to modernise their telecoms products in the UK.


Public Switched Telephone Network or PSTN is the traditional telephone landline you would have installed at home, but lots of businesses still use this 19th century technology to operate.

Integrated Services Digital Network or ISDN is a technology designed in the 80s which allowed customers to make multiple calls at the same time over a single telephone circuit.

Both systems are now outdated, have large operating costs and provide an unreliable user experience when compared to newer telecoms systems available on the market.

IP Technology

IP or Internet Protocol is the obvious replacement for PSTN and ISDN. This technology has been adopted by many small, medium and large businesses and is the technology behind household names such as Skype and WhatsApp. IP systems work by turning analogue voice into digital signals that are then transferred through the internet.

How will this affect BT Customers?

As of September 2023, businesses will no longer be able to purchase a traditional PSTN or ISDN phone system from BT.

Existing BT customers will need to swap their system for a VoIP solution when their contract is due for renewal or look elsewhere for an alternative solution. If any affected BT customers fail to switch to an alternative telecom system, they will be left without a service from December 2025!

Plans for the Future

It is important that BT customers know it is their responsibility to ensure services such as lifts, and alarms have the required connectivity to function as intended. IP technologies may not be the best option in these circumstances due to power issues and insurance criteria of a power outage.

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