The UK’s big PSTN switch off

What is the big switch off?

The UK’s Big Switch Off is the name given to the process of phasing out the old PSTN analogue phone network and replacing it with a digital one. As part of its efforts to modernise the UK’s telecoms infrastructure Openreach have not offered new analogue lines since September 2023 and will be gradually terminating ALL existing PSTN and ISDN lines by the end of 2025. These systems are running on old outdated technology which haven’t kept up with the demands of modern communication and are expensive to maintain. Much like the shift from Analog to Digital television back in 2012 many people will need to upgrade or change their existing telephony equipment. 

If you are using an one of these systems or something that relies on them (Alarm System, Fax, EPOS etc) you should start the process of moving these over to avoid disruption.

Who will be affected by the big switch off?

Millions of residential individuals and businesses will all need to move away from PSTN and ISDN by the end of 2025. 

This means that anyone who uses a landline phone, a fax machine, an alarm system, a lift emergency phone, a payment terminal or any other device that relies on the PSTN will need to upgrade their equipment and services to be compatible with the new digital only network.

How does VoIP work?

With analogue phone lines your voice call is done directly on the copper telephone line itself. The caller’s voice is translated in to electrical pulses on the wire, this signal is then routed via telephone exchanges to the wires attached to the callee’s phone.

VoIP works differently by converting the audio information into digital packets which are sent over the internet. This is done via codec standards which COmpress and DECompress  the audio signal. This is the same process as WhatsApp, Zoom or Teams calls.


What is VoIP?

Voice over Internet Protocol (VoIP), which uses broadband connections to transmit calls over the internet. VoIP offers more features and functionality than the PSTN.

What are the benefits of using VoIP over PSTN?

  • Call Quality. Analog phone signals were subject to interference such as hissing or popping on the line. These were often caused by the condition of your physical telephone line, your environment and the distance to the telephone exchange. VoIP doesn’t suffer from this interference as it’s signal is digital.
  • Flexibility. Many VoIP systems can be used from different devices and locations, not just tethered to your phonelines at home or in the office. You can have your number available anywhere you have an internet connection. Depending on your service you can also make multiple calls at once.

What is PSTN?

PSTN stands for Public Switched Telephone Network, which is the traditional phone network that uses copper wires and circuit switching to connect calls. It is also known as Plain Old Telephone Service (POTS). This was introduced in the Victorian era and was a simple but effective way of connecting telephone systems together before the advent of digital technology.

What is ISDN?

ISDN stands for Integrated Services Digital Network. It is a set of communication standards for transmitting voice, video, data and other network services over digital lines, usually copper wires. ISDN was developed in the 1980s as a way to digitize the public switched telephone network and provide better quality and speed than analogue systems.

Although it was originally much more capable that PSTN lines it has now become redundant due to the improvements in VoIP technology.


Will my existing phone stop working?

If you are using a non-VoIP phone system, then yes. You will need to switch to a VoIP system to continue receiving and making calls.

Who is Openreach?

Openreach is responsible for maintaining and upgrading the UKs public telephone systems and communication network. They are part of the BT Group. If you use any communication systems that use the general public like ADSL, VDSL, FTTC or FTTP broadband connections, you are using the Openreach network.

Contact us

If you would like to find out more information about the UK’s PSTN switch off or would like to discuss your phone system please reach out to us via one of the contact methods below or the contact form.


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