If your business still relies on a traditional ISDN or PSTN phone line, the clock is now genuinely running out. On 31st January 2027, BT Openreach will permanently switch off the old ISDN network across the UK, and any business still using it on that date will lose the ability to make and receive calls through it.

That might sound like a long way off. It isn’t. Migrating a business phone system properly, porting numbers, configuring call routing, training staff, testing everything works, takes time, and the closer we get to the deadline, the more businesses will be trying to migrate at once. We’re already seeing installation slots tighten up locally as awareness spreads.

Here’s what you actually need to know, and what to do about it.

Why is ISDN being switched off?

Openreach’s copper-based ISDN network is decades old and increasingly expensive to maintain. The UK’s telecoms infrastructure is moving entirely to full-fibre and IP-based networks, which is why every business phone system now needs to run over broadband via VoIP (Voice over Internet Protocol) instead of a traditional phone line.

This isn’t optional and it isn’t a sales tactic from telecoms providers, it’s a national infrastructure change happening whether you engage with it or not.

What happens if you don’t move in time?

If your ISDN lines are still active on the switch-off date, they simply stop working. That means:

• No inbound or outbound calls through your existing phone system
• Any connected services relying on ISDN, such as some alarm systems, card machines, and lift lines, may also be affected
• No warning call, no grace period, the network is just gone

For a business that depends on the phone ringing, trades, professional services, healthcare, retail, that’s not a minor inconvenience, it’s a direct hit to revenue and customer trust.

The good news: VoIP is better, not just newer

This isn’t a like-for-like swap you’re being forced into reluctantly. A modern hosted VoIP system genuinely does more than the ISDN line it replaces:

• Calls follow you: answer your office number from a mobile app or laptop, wherever you’re working
• No hardware headaches: no on-site phone system box to maintain or repair
• Easier scaling: add or remove users in minutes as your team changes, without an engineer visit
• Lower running costs: most businesses see a reduction in monthly line rental once they’ve moved
• Built-in resilience: if your office loses power or internet, calls can be rerouted instantly to mobiles so you never miss a call

What should you do now?

1. Find out what you’re currently on: if you’re not sure whether your lines are ISDN, PSTN, or already digital, it’s worth checking rather than assuming
2. Don’t wait for your existing contract to naturally end: many businesses assume they can leave it until renewal, but if that renewal date falls close to or after January 2027, you’ll be migrating under pressure, not on your terms
3. Get a proper migration plan, not just a new SIM in a drawer: a good migration includes number porting, call flow setup, staff handsets or apps, and testing before you go live, not just a login and good luck
4. Choose a provider who’ll actually be there afterwards: VoIP is reliable, but when something does need adjusting, a new starter, a change to opening hours routing, you want a real person to call, not a support ticket into a queue

How Complete ICT can help

We’ve been guiding Staffordshire and Cheshire businesses through telecoms changes since 2010, and the ISDN switch-off is exactly the kind of transition we handle end to end, from working out what you currently have, through to a fully configured hosted VoIP system with no long multi-year tie-in contract.

Because we’re independent, we’re not trying to push you towards one network or system, we look at what actually fits your business and get you set up with a dedicated local point of contact, based here in Newcastle-under-Lyme, for whenever you need support.

Don’t leave your migration until the queues build up. Get in touch today for a free, no-obligation review of your current setup and a clear plan for moving across well before the 2027 deadline.

Call us on 01782 346493, email enquiries@complete-ict.net, or contact us here to book your free review.

There are some simple ways in which data usage can be managed and reduced so you can carry on using your business mobile for your everyday work and communications.

There are some simple ways in which data usage can be managed and reduced so you can carry on using your business mobile for your everyday work and communications.

Voice over IP Technology (VoIP) is incredibly versatile and cost-effective for small to medium-sized businesses.

VoIP systems are suitable for employees wherever they are based and calls can be seamlessly transferred from office phone to mobile.