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ISDN and PSTN Switch off 2025

What is the PSTN and ISDN Switch Off?

News 17th February 2021

The Public Switch Telephone Network (PSTN) is ageing and will reach the end of life in December 2025. The PSTN supports a number of Openreach products that Communication Providers (CPs) purchase at regulated pricing and often sell to businesses and consumers, wrapped up in their own line rental, broadband and call package deal. These include Wholesale Line Rental (WLR) and Integrated Services Digital Network (ISDN).

ISDN is available in two common variants: ISDN2 supports channels in pairs and you can have between 2 ISDN channels or 8 ISDN channels. ISDN30 is provided for larger business customers usually, with options to have between 8 ISDN channels and 30 ISDN channels on each service. A single ISDN channel will provide a customer with 1 concurrent call at a time. At the end of December 2025 traditional telephony, including fixed lines and services in the Public Switch Telephone Network (PSTN) will be switched off and withdrawn from service.

The Public Switch Telephone Network allows calls to be made over copper telephone lines and fibre telephone lines using analogue signalling and is known as “traditional telephony”. As broadband services have increased in reliability and quality over the past 10 years, the PSTN has evolved to support this change to an almost completely digital network using digital technology. This means there will no longer be a requirement for the majority of traditional fixed-line telephony users for fixed-analogue services in the coming years and traditional fixed lines and calls will cease to exist. The priority for Openreach moving forward, is to maintain a high availability fibre first network, as a result, their legacy infrastructure and equipment serving the PSTN is now ageing and becoming more difficult to maintain.

This will affect everything from Alarm Lines, Analogue Lines, FttC (eventually), ADSL, ISDN, LLU etc, and although there is a suite of services being planned to replace these, the detail and pricing is still evolving.  So this is an issue to keep an eye on over the next 12-24 months and speak to your suppliers about.  Give us a call if you need to look at replacing legacy telephony services and we’d be pleased to provide info and pricing.


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