PSTN Switch-Off 2027: What Your Business Needs to Do Now

The UK's Public Switched Telephone Network is being switched off. By January 2027, Openreach and other network providers will stop supporting traditional analogue and ISDN phone lines entirely. If your business still relies on these services, you need to act now — not in six months, now.

This guide explains what the PSTN switch-off means, which services are affected, and gives you a practical checklist to make sure your business is ready well before the deadline.

What Is the PSTN Switch-Off?

The PSTN (Public Switched Telephone Network) is the copper-based telephone infrastructure that has carried voice calls in the UK since the 1800s. It includes:

• Traditional analogue phone lines (POTS — Plain Old Telephone Service)
• ISDN2 and ISDN30 digital circuits
• Services that rely on copper pairs — alarm lines, fax machines, EPOS terminals, door entry systems, and lift emergency phones

Openreach, the UK's largest network infrastructure provider, is retiring this network and replacing it with an all-IP (Internet Protocol) infrastructure. BT and other providers have been gradually migrating customers since 2023, with a hard stop date of January 2027.

Why Is It Happening?

The copper network is ageing, expensive to maintain, and increasingly unreliable. Modern IP-based networks offer:

• Better call quality and reliability
• Lower maintenance costs for network operators
• Support for unified communications, video, and data alongside voice
• Scalability that copper simply cannot match

The switch-off is not optional. Openreach has stopped selling new ISDN and analogue lines in most exchange areas, and existing lines will cease to work after the cut-off date.

What Happens If You Do Nothing?

If your business has not migrated by the deadline:

• Your phone lines will stop working — no inbound or outbound calls.
• Any devices connected to analogue lines (alarms, fax, EPOS) will also fail.
• You will have no dial tone and no way to receive customer calls.
• Emergency migration will be rushed, disruptive, and more expensive than a planned move.

There is no extension. The infrastructure is being physically decommissioned.

Your PSTN Switch-Off Checklist

Use this checklist to prepare your business. Work through each item and tick it off:

1. Audit your current phone services

• List every analogue line, ISDN circuit, and copper-dependent service your business uses.
• Include all sites — head office, branches, warehouses, and remote locations.
• Identify non-voice services on copper: burglar alarms, fire alarms, lift lines, EPOS, franking machines, fax, and door entry systems.

2. Check your broadband

• VoIP requires a stable internet connection. Check your broadband speed and reliability at every site.
• If you are on ADSL (which also runs over copper), you will need to move to FTTP, SoGEA, or a leased line.
• Ensure your router supports QoS (Quality of Service) to prioritise voice traffic.

3. Choose a VoIP solution

• Options include hosted VoIP platforms, SIP trunking with an on-premises PBX, or Microsoft Teams with Direct Routing.
• Consider your business needs: number of users, call volumes, remote working, and integration with existing systems.
• Get quotes from at least two providers and compare features, support, and pricing.

4. Plan number porting

• You can keep your existing phone numbers by porting them to your new VoIP provider.
• Start the porting process early — it can take 10–20 business days depending on the number type and losing provider.
• Confirm geographic number availability if you are adding new numbers.

5. Address non-voice services

• Alarms: Contact your alarm monitoring company. Most offer IP or GSM (mobile) communicators as replacements.
• Fax machines: Switch to a fax-to-email service or online fax platform.
• EPOS terminals: Most modern terminals use broadband or 4G. Contact your payment provider.
• Lift emergency phones: GSM gateways are the standard replacement. Your lift maintenance company can advise.
• Door entry systems: SIP-compatible door entry panels are available, or use a GSM intercom.

6. Upgrade your internet if needed

• If your broadband is not fast or reliable enough for VoIP, arrange an upgrade before migrating your phone system.
• FTTP (fibre to the premises) is ideal. Where unavailable, SoGEA with FTTC provides a solid alternative.
• For businesses with high call volumes or multiple sites, consider a dedicated leased line or SD-WAN.

7. Run a pilot

• Migrate a small group of users or a single site first.
• Test call quality, features, and reliability for at least two weeks before rolling out company-wide.

8. Schedule the full migration

• Work with your provider to set a migration date with minimal disruption.
• Communicate the change to staff and update any published phone numbers if they are changing.
• Plan for a brief overlap period where both old and new systems are active.

Timeline: When Should You Start?

If you have not already started, the time is now. Here is a realistic timeline:

• Month 1: Audit lines and services, check broadband, shortlist providers.
• Month 2: Choose a provider, sign contracts, begin number porting.
• Month 3: Deploy hardware (if needed), configure the VoIP system, run a pilot.
• Month 4: Full migration, staff training, decommission old lines.

Four months is comfortable, but delays in number porting or broadband upgrades can extend the timeline. Do not leave it until Q4 2026 — providers will be overwhelmed with last-minute migrations.

How Connection Technologies Can Help

We have been migrating UK businesses from PSTN and ISDN to VoIP since the switch-off programme began. Our team handles the entire process — audit, solution design, number porting, installation, and ongoing support — so you do not have to manage it yourself.

For a deeper dive into enterprise voice options, read our guide to enterprise VoIP and UCaaS solutions. If SIP trunking is part of your migration plan, see our explanation of how SIP trunking works and what it costs.