Skip to main content
Nottingham: 0115 718 2881
Performance Networks / Blog / ISDN Switch Off

ISDN Switch Off

The ISDN and PSTN switch-off is scheduled for December 2025, which, as you know, in the business world, will be here before we know it. For your business continuity, it’s important that you find out more about this switch now and how it will impact your business.

What is PSTN?

A Public Switched Telephone Network (PSTN) is a telecommunications network that enables voice communication between users at different locations. Introduced in the 1800s, PSTN uses a network of copper wires to transmit information. For many years, businesses have relied on PSTN as their primary method for making phone calls and sending fax transmissions, remember them?!

What is ISDN?

ISDN, which stands for Integrated Services Digital Network, is a set of communication standards for digitally transmitting voice, video, data, and other network services over traditional PSTN circuits. Introduced by BT in the UK in 1986, ISDN replaced old analogue landlines with digital lines, offering enhanced features not available with classic telephone systems.

BT ISDN Switch Off

Way back in 2015, BT announced that it would be shutting off the ISDN and PSTN services by December 2025. They had realised that neither of these technologies could provide the quality or volume of voice data its customers required in this ever-increasing digital landscape.

From 2025 all calls will be made through the Internet, also known as VoIP or Voice Over Internet Protocol. VoIP can make use of the superfast speeds that come with fibre optic connectivity.

Why Turn Off the ISDN Lines?

But why turn off the ISDN lines? Well, although ISDN has had many improvements since the 80s, the premise remains the same and is now simply outdated. Broadband speeds are just supremely faster and perform at a greater level than ISDN can compete with, which is important for any business that wants to provide the best services to its customers and the best tools for its employees to do their jobs.

Traditional ISDN lines offer much less flexibility, and with a traditional line, your business number is tied to a physical location unless you spend time putting in redirects, which can be time-consuming and messy.

Scalable and flexible options to support cloud-based systems and remote working environments make VoIP and IP technology a more sensible option. It also makes no financial sense for BT to keep improving a network with a shortening life span. Turning off ISDN means BT can shift their focus to bettering their VoIP services and futureproofing them to meet the growing demand for IP technologies.

VoIP or SIP?

Voice over Internet Protocol (VoIP), or IP telephony, is a method and suite of technologies for delivering voice and multimedia sessions over IP networks. With VoIP, analogue voice calls are converted into packets of data. These packets travel over the public Internet or any private IP network, like emails.

Session Initiation Protocol (SIP) is a set of rules used in multimedia communications to initiate, modify, and terminate data transfer between different users. SIP enables VoIP calls by managing the creation, modification, and termination of sessions, whether two-way or multi-party conference calls.

✓  Opt for VoIP to upgrade to an entirely new phone system when transitioning from ISDN.

✓  Choose SIP if you prefer to retain your existing phone system during the switch.

How to Switch from ISDN to Hosted VoIP

Switching from ISDN to VoIP is straightforward. You will need to determine your business requirements and the phone extensions you need, but as your needs change, VoIP adjustments can be easily made.

You will also need to ensure your internet connection supports VoIP. An upgrade will be required if your network lacks the bandwidth for voice and additional features. You must also check if your current office phone system supports VoIP and replace it with an IP-compatible phone system if it doesn’t. Choosing a hosted VoIP phone system is ideal if you have ISDN lines and prefer not to invest in an on-site phone system.

You can smoothly transition from ISDN to a hosted VoIP solution by addressing these factors.

To ensure your VoIP system works as well as it can, you must ensure your bandwidth is good enough to deliver the voice and other features of VoIP. If you need help or advice with improving your broadband, get in touch, our experienced team can help with fibre broadband solutions or Fibre To The Cabinet [FTTC].

Benefits For Switching

Switching to VoIP comes with many benefits. First, it can dramatically cut call charges, line rental, and infrastructure costs. VoIP also introduces a range of new capabilities that can transform how your business operates, offering features like presence status, exchange functions, switchboards, CRM integration, and the ability to call on any device—many of which are unavailable or too costly on traditional landline systems. Service efficiency is another advantage, as VoIP provides greater control over calls, allowing for faster and more effective customer interactions while offering insights for performance improvement. Communication is enhanced by integrating phone calls, emails, messaging, scheduling, staff status, apps, and CRM into a unified system, bringing voice calls into the digital world. Additionally, VoIP systems are robust, featuring disaster recovery measures designed to minimise downtime and data loss. Regular backups of call recordings and configurations ensure that if a system failure occurs, it can be quickly restored, usually within an hour.

Prepare Your Business for the ISDN Switch-Off

If you’ve already switched from ISDN to an IP-based system, congratulations! If you haven’t, now is the perfect time to explore alternatives to ensure your business is prepared for the ISDN switch-off. Start by checking if your current phone system is IP-compatible. If not, you’ll need to invest in a newer system. If it is compatible, consider replacing your ISDN service with SIP Trunking.

Remember, switching to IP technology heavily relies on a stable internet connection, so you’ll need to assess if your current connection is sufficient with a wifi survey. If not, upgrading to a fibre optic connection or an Ethernet-based leased line might be necessary. The transition process can take a few weeks, depending on the size of your business and existing infrastructure, but we can take the burden of the process with our expertise in business wifi solutions. We’ll handle the porting and work closely with you to ensure minimal disruption to your business activities during the ISDN switch-off.

Let’s get connected

We’ll find the solution, performance guaranteed. Get in touch to find out more.

Get in touch

Contact our team for a free no obligation quote

    Thank you for your enquiry, one of our team will be in touch very soon.

    Partnered with industry leaders

    Cisco partner logo purple
    aruba logo purple
    Ruckus logo purple
    Extreme logo purple
    cisco meraki logo purple
    fortinet logo purple
    All our partnerships