PSTN Switch-Off: What UK Businesses Need to Do Before January 2027

What is the PSTN switch off and why is it happening?

The Public Switched Telephone Network (PSTN) is the analogue copper infrastructure that has carried UK voice calls for over a century. Openreach is retiring it and replacing it with all-IP delivery, where calls travel as data over broadband. The ageing copper network is costly to maintain and cannot match modern IP systems.

Openreach has stated that running two parallel networks — copper and fibre — is neither economically nor technically sensible. Retiring the PSTN concentrates investment in full-fibre and IP infrastructure. Around 2.8 million lines still rely on the PSTN, more than 500,000 of them serving business premises (Openreach, February 2026), and each one must migrate before the deadline. For the regulatory background, see Ofcom's guidance on the move to digital landlines. If you are weighing your options now, start with our business VoIP pillar guide.

When is the PSTN switch off deadline?

The switch off is a phased programme, not a single event. The stop-sell of new analogue and ISDN lines is already in force across most exchanges, and the final cut-off is fixed for 31 January 2027. There is no planned extension.

What does the switch off mean in practice for businesses?

Any service that depends on a traditional phone line will stop working after the cut-off. The obvious impact is your desk phones, but the PSTN carries far more than voice calls. Every connected service must be audited and migrated, or it will simply go dark on the deadline.

Systems commonly overlooked in migration planning include:

• Fax machines on a phone line — still used in legal, medical, and property sectors
• PDQ card payment terminals that dial out over a landline to process transactions
• Fire and intruder alarms with dedicated PSTN lines to a monitoring centre
• Lift emergency telephones — a legal two-way call requirement under the Lifts Regulations 2016
• Door entry systems that call residents or staff over a phone line
• CCTV and building management systems that report status or alerts via PSTN

A non-functioning lift emergency phone is a compliance breach that can trigger enforcement action, so alarm and safety lines must be addressed in parallel with your phone system — not as an afterthought.

Does the switch off affect your broadband?

If you use FTTC (Fibre to the Cabinet), the final copper run from the street cabinet to your premises rides on the PSTN — so the switch off can touch your broadband as well as your phones. Openreach is migrating FTTC to SOGEA, an all-IP product that drops the phone-line dependency.

In most cases your broadband continues, but on older FTTC products you must confirm with your provider that the service will be migrated, not terminated. Where reliability is critical, moving to FTTP or a dedicated leased line removes the risk entirely and delivers the stable, symmetric bandwidth VoIP calls need.

What are your VoIP migration options?

The usual path is to replace your ISDN-connected PBX with a cloud platform. There are two principal routes, and the right one depends on the age and SIP-compatibility of your existing kit. A SIP trunk keeps your PBX; a hosted phone system or UCaaS platform replaces it entirely.

Microsoft Teams Phone is the most widely adopted hosted option for organisations already on Microsoft 365 — see Microsoft's Teams Phone documentation and our guide to VoIP and Microsoft 365 integration. Microsoft reports Teams now has over 320 million monthly active users globally. Beyond meeting the deadline, modern VoIP adds web call management, mobile apps, call recording, auto-attendant, and analytics that ISDN cannot provide. Most UK businesses see a 30–50% cut in monthly telecoms costs after migrating, largely from removing ISDN line rental (typical UK 2026 range).

How much does it cost to migrate from ISDN to VoIP?

Migration cost depends on line count, PBX complexity, and whether you need new handsets. For most businesses the ongoing VoIP cost is lower than current ISDN rental, because line rental is the single largest saving. AMVIA gives a fixed-price quote after assessing your setup, so there are no surprises.

ISDN line rental alone costs £25–£50 per channel per month, so a 30-channel ISDN30 circuit can exceed £1,000 a month before any calls are made. VoIP typically delivers the same capacity for 30–50% less, with lower per-minute rates and no PBX maintenance contract to fund.

Why migrate with a security-first provider?

VoIP runs over your data network, which makes voice a security concern, not just a telecoms one. Toll fraud, eavesdropping, and 999 emergency-call obligations all need handling correctly. Migrating with a provider that treats VoIP security as standard means encryption, fraud monitoring, and accurate emergency location are built in from day one.

Your new system must provide 999 access with accurate location data, as required by Ofcom rules — read Ofcom's rules on emergency call access. This matters most for multi-site organisations and remote workers, where a single accountable provider keeps connectivity, voice, and security under one roof.

PSTN switch off action checklist

Take these steps well ahead of the 31 January 2027 deadline:

• Audit every PSTN and ISDN line — including alarms, lifts, payment terminals, and fax machines, not just desk phones
• Test your connectivity — bandwidth, latency, jitter, and packet loss must support clean voice
• Choose your path — SIP trunking or hosted VoIP/UCaaS, assessed objectively
• Plan number porting early — porting takes 7–14 working days and queues lengthen as 2026 demand peaks
• Migrate non-telephony services — alarms, lift phones, and PDQ terminals move to IP or 4G, each with its own lead time
• Confirm 999 compliance — accurate emergency location for every site and remote user