Planning for the PSTN switch-off in 2027 often starts with the office phone system. In older London buildings, that’s only one part of the problem. Lift phones, alarm systems and payment terminals can run on the same ageing network, often without anyone on site realising it.
The PSTN Switch-Off 2027 Deadline
The Public Switched Telephone Network, or PSTN, is the copper-based system that has carried UK phone calls for decades. Openreach and BT are retiring it on 31 January 2027, with no further extensions planned.
At the end of July 2026, Openreach reported that around 1.5 million UK lines were still running on this legacy network, down from 1.9 million in June. Roughly 350,000 of those were business premises, which is why the PSTN switch-off for businesses carries a harder deadline than it does for residential lines. Business lines won’t get the same fallback protection being offered to vulnerable residential customers, so there are a significant number of businesses with work still to do.
Legacy line rental has also become more expensive as the deadline approaches. Openreach’s wholesale WLR basic rental rose by 20% on 1 April 2026, by a further 40% on 1 July 2026, and by another 40% on 1 October 2026, effectively doubling the price in the final months before the switch-off. Planning the move now avoids paying more for a service that’s being withdrawn regardless.
What PSTN Replacement Affects Beyond Phones
A phone system swap is the obvious trigger for PSTN replacement, but older buildings often have other equipment wired into the same analogue lines. Government guidance on moving to digital landlines lists several examples businesses should check, including analogue phones, fire and security alarms, payment terminals, lifts and intercom systems, alongside broadband services that still rely on the copper network.
Not every piece of equipment in an older building will depend on PSTN, and the exact dependencies vary by premises and by what’s installed. A lift engineer or alarm maintenance contractor will know whether their specific system uses an analogue line to dial out, and checking with them directly is the quickest way to find out. Identifying what’s connected to the old network in the first place matters more than assuming it’s limited to desk phones.
Why Canary Wharf and Docklands Offices Need a PSTN Audit
Growing businesses in London often inherit more than they realise when they move into or expand within an existing office. Phone lines and alarm systems installed by a previous tenant don’t always come with a clear record of what’s connected to what. Door entry setups are often missed too, and in buildings across Canary Wharf and the Docklands, there’s often no record of them at all.
As a Canary Wharf business ourselves, we see this pattern regularly across the Docklands, where converted warehouse buildings and newer office towers often sit on the same street, each with a different wiring history underneath.
Checking the phone contract alone can miss equipment that sits elsewhere in the building, on a different account, or installed by a different supplier entirely. This is particularly common in shared or serviced office buildings, where a managing agent or landlord may hold contracts for building-wide systems that an individual business never sees on its own invoices. A proper audit starts with a list of every connection and piece of equipment on the premises, then works out which of those still rely on the legacy network and which need replacing or reconfiguring before January.
Preparing for the Digital Phone Switchover Before 2027
With several months left before the deadline, there’s still time to work through this properly instead of rushing things in January. The starting point is understanding what currently runs through your phone lines and broadband connection, what needs to move across as part of the digital phone switchover, and what falls to specialist equipment suppliers to handle separately.
At Platform 365, we start by looking at a business’s whole communications setup, including VoIP and mobile services, before recommending any changes. That also covers the collaboration tools a team relies on day to day, since all of it needs to work together once the phone lines change. Alarms and lifts sit outside that review, and so does door entry equipment. The right people to confirm PSTN dependency are the specialist installers or maintenance providers for each system.
The office phone system is the easiest part of the PSTN switch-off in 2027 to sort out, since it’s the part every business already expects to deal with. The harder part is everything else wired into the same network without anyone keeping a record of it, which is why starting with a full list of what’s connected matters more than starting with a replacement phone system.
If you’d like to talk through your business’s phone and connectivity setup before the January deadline, our Communications team can walk through what’s currently in place and what moving to VoIP for businesses would involve. Get in touch and we’ll take it from there.
FAQs
Has the PSTN switch-off date been delayed before?
Yes. The original end-2025 target was pushed back to give extra time for vulnerable telecare customers to migrate safely. Openreach has confirmed there’s no further delay planned, and 31 January 2027 is now the fixed date for business and residential lines.
How do I check if my business still uses a PSTN line?
Your phone or broadband provider can confirm this from your account details. Asking directly is more reliable than guessing from the equipment alone, since many businesses have already been moved onto digital lines without realising it.
What’s the difference between PSTN and VoIP?
PSTN is the older, copper-based line that carries calls through local exchanges. VoIP sends calls over the internet instead, using the same connection as your broadband. The practical difference for an office is that VoIP needs a stable internet connection, while PSTN worked independently of it.
