The phone on your desk has probably worked the same way for years, but that’s about to change. The UK’s traditional phone network is soon being switched off for good as part of the government’s project to transition from analogue to digital landlines. So, every business still running on old-style lines will need to move to something new before the deadline.
This is the PSTN switch-off explained the way a business owner would want it. We’ll walk through what’s changing, what happens if you leave it too late, and why Microsoft Teams Phone is a practical, cost-effective replacement worth moving to now.
What Is the ISDN and PSTN Switch-Off?
The PSTN (Public Switched Telephone Network) is the copper-wire system that’s carried UK phone calls for decades. ISDN (Integrated Services Digital Network) is its business cousin, running multiple lines over the same ageing copper. Both are being retired because the infrastructure is costly to maintain and simply can’t keep up with how businesses communicate today.
The full PSTN and ISDN switch-off in the UK is set for 31 January 2027. That might sound like plenty of time, but it isn’t really. A national “stop sell” has been in place since September 2023, so you can no longer order or upgrade these old lines. Openreach is also switching exchanges over in phases, which means your line could stop working well before the final deadline.
And it’s not just your phones. Alarms, card machines, lifts and door entry systems often run over these same lines, so the ISDN switch-off affects more of your business than you might expect.
The Risk of Leaving It Too Late
Research from Zen Internet found that only 18% of small businesses have a replacement in place, and nearly one in ten don’t even realise the switch-off is happening at all.
Leaving it late carries two real risks:
Losing service altogether – If your exchange migrates before you’ve moved, your lines simply stop working, as does anything connected to them.
The last-minute rush – As the deadline nears and everyone scrambles at once, providers get booked up, number transfers take longer, and prices creep up. The businesses that wait end up with fewer options and less control.
It’s a bit like booking a removals firm on moving day. The longer you leave it, the slimmer the pickings and the more you’ll pay for them.
How Teams Phone Works as the Replacement
So what do you move to? Instead of calls travelling down a copper line, they travel over your internet connection. This is often called VoIP, and for business in Birmingham it’s the standard replacement. Microsoft Teams Phone takes it a step further by putting your phone system inside the Teams app your team probably already uses every day.
There are three reasons it’s such a strong fit:
Cost: There’s no separate line rental; calls run over the internet you already pay for, and you’re maintaining one platform instead of two. For most businesses, that’s a straightforward saving.
Efficiency: One number follows you across desk phone, laptop and mobile, so your team can work from anywhere without missing a call. Calls, chat, meetings and files all live in one place. It’s built for hybrid and flexible working.
Security: A modern cloud phone system is actively maintained, updated and encrypted, unlike ageing copper kit. How you handle calls is part of your security picture too.
Why Birmingham Businesses Should Act Now
It’s tempting to file this under “deal with it later”, but for Birmingham businesses ‘later’ is closer than it looks. West Midlands exchanges are part of the active rollout, so this isn’t some distant national headline. It’s happening on your doorstep.
Moving early flips the whole thing in your favour. Instead of a rushed switch under deadline pressure, you get to choose on your own terms: time to test properly, train your team, and move your numbers across without a scramble. You also start enjoying the benefits sooner, rather than treating the change as a last-minute chore.
Put simply, the businesses that move early are the ones in control. Making the switch to Teams Phone now is a smart operational upgrade that you’ll feel the benefit of straight away.
How MTS Technology Handles the Migration
MTS Technology has supported businesses across Birmingham and the wider Midlands since 1973, from our base in Tamworth. We’ve seen how these transitions play out, and we know the word “migration” makes owners picture downtime, dropped calls and disruption. Handled properly, it’s none of those things.
Here’s how we approach it. We start by auditing what’s actually running on your old lines, phones included, but also the alarms, card machines and other kit that quietly depend on them. From there we plan the move, port your existing numbers so nothing changes for your customers, set up and test Teams Phone, and get your team confident using it. No loss of service, no nasty surprises.
The switch-off deadline is fixed, but the disruption people worry about isn’t inevitable. It comes from leaving it late, not from the move itself.
Not sure where to start? Book a free discovery call, and we’ll map out exactly what your business needs to move off the old lines.
FAQs
When is the PSTN and ISDN switch-off?
The full switch-off is 31 January 2027. But a national “stop sell” has been in place since September 2023, so you can’t order or upgrade old lines now, and Openreach is switching exchanges over in phases. That means your line could stop working before the final deadline.
What happens if I don’t switch in time?
Your old lines simply stop working, and so does anything connected to them, including alarms, card machines and door entry systems. You’d lose the ability to make and take calls until a replacement is in place, which is exactly the disruption moving early avoids.
Can I keep my existing phone numbers?
Yes. Your current numbers can be ported across to Teams Phone, so nothing changes for your customers. There’s no need to reprint stationery or update your website.
Is Teams Phone reliable enough for business?
Yes, provided you have a stable internet connection. Many businesses find a modern cloud phone system more reliable than ageing copper lines because the infrastructure is newer and actively maintained.
