{"id":3009,"date":"2024-12-03T14:28:15","date_gmt":"2024-12-03T14:28:15","guid":{"rendered":"https:\/\/client-acora.s.nomatter.dev\/one\/?p=3009"},"modified":"2026-03-31T10:45:23","modified_gmt":"2026-03-31T09:45:23","slug":"isdn-pstn-switch-off","status":"publish","type":"post","link":"https:\/\/acora.com\/one\/news\/article\/isdn-pstn-switch-off\/","title":{"rendered":"ISDN & PSTN Switch Off"},"content":{"rendered":"

This is a\u00a0quick 5 minute guide<\/strong>\u00a0to the\u00a0ISDN<\/strong>\u00a0and\u00a0PSTN switch off<\/strong>, updated for 2024.<\/p>\n

Known as the \u2018BT ISDN Switch Off\u2019, this will be a huge shift in the way people make phone calls in the UK.<\/p>\n

The official final switch off will happen in\u00a0December 2025<\/strong>.<\/p>\n

Just under 2 more years!<\/p>\n

For business continuity, it is vital companies learn about it and make the necessary changes now.<\/p>\n

So let\u2019s take a look at\u00a0what it is<\/strong>\u00a0and\u00a0what you need to do<\/strong>\u00a0to prepare.<\/p>\n

 <\/p>\n

What is PSTN?<\/h3>\n

A\u00a0Public Switched Telephone Network (PSTN)<\/strong>\u00a0refers to a telecommunications network which allows subscribers at different sites to communicate by voice.<\/p>\n

Introduced during the 1800s PSTN allows for information to be transmitted through a network of copper wires.<\/p>\n

PSTN has been used by businesses as their primary method of transmitting phone calls and fax transmissions for several years.<\/p>\n

What is an ISDN line?<\/h3>\n

ISDN<\/strong>\u00a0stands for\u00a0Integrated Services Digital Network<\/strong>.<\/p>\n

It\u2019s a group of communication standards that use digital transmission to make phone calls, video calls, transmit data and other network services over the circuits of the traditional\u00a0PSTN (Public Switched Telephone Network)<\/strong>.<\/p>\n

In 1986, BT introduced\u00a0ISDN<\/strong>\u00a0in the UK.<\/p>\n

It replaced old analogue landlines to digital lines, adding features that weren\u2019t available with a classic telephone system.<\/p>\n

What is the 2025 ISDN switch off?<\/h3>\n

BT announced back in 2015 they will shut off their ISDN and PSTN services completely by December 2025.<\/p>\n

Neither of these technologies are capable of delivering the\u00a0volume<\/strong>\u00a0or\u00a0quality<\/strong>\u00a0of voice data needed in this increasingly digital world.<\/p>\n

Voice calls in the future will be made over the internet.<\/p>\n

This is often referred to as\u00a0VoIP (Voice over Internet Protocol)<\/strong>, which makes use of newer technologies such as\u00a0fibre optic connectivity<\/a>.<\/p>\n

Why is ISDN being switched off?<\/h3>\n

Although ISDN has been improved a lot since 1986, the network has remained relatively unchanged and is now\u00a0a little outdated<\/strong>.<\/p>\n

Broadband internet connection speeds are\u00a0a lot faster<\/strong>\u00a0and at\u00a0a higher level<\/strong>\u00a0than ISDN.<\/p>\n

In short, ISDN can\u00a0no longer compete<\/strong>.<\/p>\n

Traditional ISDN lines also\u00a0offer little flexibility<\/strong>.<\/p>\n

Businesses are\u00a0tied to physical locations<\/strong>.<\/p>\n

With the shift to cloud-based systems that are scalable and flexible for remote working,\u00a0IP technology is a better choice<\/strong>\u00a0to meet these demands.<\/p>\n

In 2015, BT decided it\u00a0didn\u2019t make financial sense<\/strong>\u00a0to keep making improvements to the ISDN network.<\/p>\n

Why?<\/p>\n

Well, BT can now\u00a0focus their resources on up-to-date technology<\/strong>\u00a0like VoIP, building services for the future, whilst meeting the growing demand from businesses.<\/p>\n

\n

What will replace ISDN?<\/h3>\n

There are two options that will replace ISDN,\u00a0VoIP<\/strong>\u00a0and\u00a0SIP<\/strong>.<\/p>\n

What is VoIP?<\/strong><\/p>\n

Voice over Internet Protocol (VoIP)<\/strong>, also known as IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over IP networks.<\/p>\n

With VoIP, analogue voice calls are converted into packets of data.<\/p>\n

Packets travel like any other type of data, such as e-mail, over the public Internet and\/or any private\u00a0Internet Protocol (IP)<\/strong>\u00a0network.<\/p>\n

What is SIP?<\/strong><\/p>\n

Session Initiation Protocol (SIP)<\/strong>\u00a0is a set of rules that are used in multimedia communications to initiate and terminate data transfer between different users.<\/p>\n

It is the way you achieve a VoIP call.<\/p>\n

SIP is the technology that\u00a0creates, modifies, and terminates sessions<\/strong>\u00a0with one or more parties in an IP network, whether a two-way call or a multi-party conference call.<\/p>\n

What can I switch to?<\/h3>\n

Put simply:<\/p>\n

Choose\u00a0VoIP<\/strong>\u00a0if you want to buy a\u00a0whole new phone system<\/strong>\u00a0when you make the switch from ISDN.<\/p>\n

Or go with\u00a0SIP<\/strong>\u00a0if you want to\u00a0keep your current system<\/strong>\u00a0when you make the\u00a0switch<\/a>.<\/p>\n

How to switch from ISDN to hosted VoIP<\/h3>\n

Choosing a hosted VoIP phone system is the best option for you, if you\u00a0already have ISDN lines<\/strong>\u00a0and don\u2019t want to commit to a phone system on location.<\/p>\n

Switching from ISDN to VoIP is very simple.<\/p>\n