For many UK businesses, the PSTN switch-off still feels like a 2027 problem. The deadline is 31 January 2027, so it can be tempting to think there’s still plenty of time to deal with it. But there’s a problem with that approach: the cost of waiting has already started.
From rising legacy line charges to the operational cost of a rushed migration, delaying the move away from PSTN could leave your business paying more for an ageing service while giving you less time to replace it properly.
So, what could waiting actually cost your business?
The price of staying on legacy lines
The first cost is also the easiest to see: your line rental. Openreach has introduced staged price increases for its legacy Wholesale Line Rental (WLR) products during 2026. WLR basic rental increased by 20% in April. In July, the increase reached 40% against the previous price, with a further rise scheduled for October that will take the rental price to double its previous level. In other words, businesses that remain on legacy services aren’t simply delaying a future project.
They’re potentially paying more while they wait.
And ultimately, the migration still needs to happen.
For a business with several legacy lines, those additional charges can quickly turn waiting into an unnecessary operating cost.
The cost of migrating under pressure
Price increases are only one part of the equation. There is also the cost of having less time. Migrating in December rather than September doesn’t necessarily mean there’s less work to do. You still need to understand what is connected, choose replacement services, coordinate suppliers, arrange installation and test everything. You’re simply doing the same job against a tighter deadline. As more businesses move ahead of the January 2027 switch-off, demand for migration support and installation appointments is also likely to increase.
Planning earlier gives your business more control over when the work happens and how the migration fits around normal operations.
Waiting means some of that choice could disappear.
What does a missed PSTN dependency actually cost?
This is where the real financial risk can be hidden. When people hear “PSTN switch-off”, they naturally think about their office phones. But legacy lines can support much more than voice calls.
Your alarm system, payment terminal, lift emergency phone, door entry system or other equipment could still rely on an analogue connection. And these services don’t necessarily give you a convenient warning before causing a problem.
If a payment terminal loses connectivity, for example, the cost isn’t simply replacing the connection. It’s the potential disruption to transactions while the problem is diagnosed and fixed. The same applies to security and other business-critical systems.
That’s why the cost of an overlooked dependency can be considerably greater than the cost of planning the migration properly in the first place.
DIY or managed PSTN migration?
Does every business need a managed PSTN migration?
No.
For a business operating from one office with a straightforward setup, handling the migration internally can be perfectly reasonable. If you know exactly which lines you have, what they’re connected to and which suppliers are responsible, you may be able to coordinate the change yourself. The question is whether you’re confident you have the full picture. A managed migration becomes valuable when identifying those dependencies and coordinating different providers starts consuming internal time or introducing unnecessary risk.
Rather than simply replacing a phone line, a managed approach looks at the business as a whole before anything is disconnected.
The trade-off isn’t simply DIY versus paying someone else to do it. It’s the cost of managed support versus the internal time and potential disruption involved in coordinating it yourself.
How 4th Platform keeps PSTN migration costs predictable
At 4th Platform, we help businesses move away from PSTN without turning the deadline into a last-minute project.
That starts with understanding what you actually have.
We can identify legacy connections and the services relying on them, then build a migration plan around your business.
That means:
- identifying dependencies before anything is disconnected
- recommending the right digital replacements
- coordinating the suppliers involved
- planning and testing the cutover
- moving services on a timeline that works for your business
And if your setup is simple enough to manage internally, we’ll tell you. The goal isn’t to make PSTN migration bigger than it needs to be. It’s to make sure you understand the cost, work and risk involved before deciding how to approach it.
What is waiting actually costing your business?
The business phone switch-off deadline may be 31 January 2027, but that’s not necessarily the date that should drive your decision.
Legacy prices are already rising. The work still needs to be done. And the longer businesses wait, the less time they have to deal with unexpected dependencies.
So there’s a more useful question to ask:
Has anyone actually worked out what waiting is costing your business?
4th Platform can help you understand your current PSTN estate, identify any hidden dependencies and compare the cost of acting now with the cost of leaving it later.
Book a PSTN cost and readiness review with 4th Platform →
If your PSTN migration plan starts with buying a new phone system, you could be missing the bigger picture. The UK’s Public Switched Telephone
AI adoption is picking up fast across UK businesses. So is the number of companies who buy a tool, roll it out, and quietly
Most AI conversations start in the wrong place. A vendor pitches a tool. A demo looks impressive. A budget gets signed off. Then, months
AI is everywhere. But where should your business actually start? If you’ve looked at AI recently, you’ve probably been overwhelmed. Every week there’s a
Most business owners think they know what technology their teams use. Microsoft 365. Teams. A CRM. Job done. Then someone mentions they’re sharing files
The UK’s traditional phone network is being switched off for good. By 31 January 2027, BT will retire the Public Switched Telephone Network (PSTN),
Hybrid working is no longer a temporary adjustment for UK businesses. For many SMEs, it has become the default way of operating. The
If every member of your team spends 30 minutes a day on tasks that should take five (re-entering data, waiting for slow systems, copying
If your outbound calls are going unanswered, it may not be your team. It is your number. Across the UK, trust in phone calls
Most UK businesses are running three, four, sometimes five separate communication tools at once. Phone calls on one platform. Video meetings on another. Messages
