ISDN stands for Integrated Services Digital Network. Which sounds a lot more complicated than it actually is. Basically, ISDN is the UK's copper cable telephone network.
The UK's current infrastructure is made up of two different networks, working simultaneously to provide broadband and voice connectivity:
These two networks are installed and maintained by the network carriers, such as Openreach, Virgin and Vodafone. Your business or household can 'rent' part of this network from an internet service provider (ISP), to provide your voice and data connectivity.
Good question. There are a few different reasons why ISDN is being switched off in 2025. But the main reasons are that it is outdated, costly and slow.
ISDN is being phased out because it is being replaced by VoIP and fibre connectivity. Traditional telephone systems will soon become obsolete, and VoIP will take over as the primary method for calling.
ISDN has been around for a long time now, and as with all technology, it is reaching its expiry date and is no longer suitable for the modern age of business connectivity, on-demand streaming and mobility.
The most important thing is not to panic. ISDN is still here and although VoIP will soon replace it, there is plenty of time for you to upgrade. Most businesses are already making the move to a VoIP telephone system, stripping our their on-premise solutions in favour for cloud-based hosted VOIP.