What is being switched off
The Public Switched Telephone Network (PSTN) is the copper-based network that has carried UK landline calls for decades. ISDN, the digital service many business phone systems use, runs over the same infrastructure. Openreach and BT are retiring both, and voice services are moving to digital technology that runs over broadband, known as VoIP or IP voice.
New PSTN and ISDN lines are no longer sold nationally, and existing lines are being migrated area by area. BT's current target is to complete the switch-off by January 2027, so if your business still relies on traditional lines the time to plan is now. Check the latest timetable with your line provider, as dates for individual exchanges vary.
What it affects
The obvious item is your phone system, but many other devices quietly use phone lines:
- Phone systems connected to analogue or ISDN lines;
- intruder and fire alarms that dial out to a monitoring centre;
- lift emergency phones and door entry systems;
- card payment terminals that still use a phone line;
- franking machines, fax machines and some CCTV systems;
- telecare and other alarm devices for vulnerable people;
- broadband delivered over a phone line, which moves to a data-only product such as SOGEA or to full fibre.
A five-step plan
1. Audit your lines and numbers
Go through your phone bills and list every line, number and what it is used for. Businesses often find lines nobody can account for. Our UK phone number checker can help identify number types and ranges.
2. Find every device that uses a line
Walk the building. Check alarm panels, lift cars, comms cupboards, tills and the reception desk. Ask your alarm, lift and payment providers what their equipment needs after the switch-off; many offer IP or SIM-based replacements.
3. Choose your voice replacement
For most small and medium businesses the choice is between:
- a hosted phone system (cloud telephony), where the phone system runs in the cloud and handsets and apps connect over the internet; or
- SIP trunks connected to an existing IP-capable phone system, if it is recent and still supported.
Our comparison of cloud phone systems and traditional PBXs covers the trade-offs.
4. Make sure your broadband is ready
Voice over the internet needs a stable connection with enough upload capacity for the number of simultaneous calls. Test with our speed test, and consider a backup connection or automatic diversion of calls to mobiles if the main line fails.
5. Port numbers before cancelling anything
Your existing numbers can usually be moved to the new service. Arrange the port first, and only cancel old lines once the numbers are working on the new platform, otherwise you risk losing them.
Power cuts and emergency calls
Traditional phones were powered by the line, so they kept working during a power cut. Digital phones need mains power and a working internet connection. Plan for this: battery backup for your router and network switches, mobile apps that keep calls flowing, and a clear procedure for staff. Make sure emergency call location details held by your provider are accurate for each site.
Common mistakes to avoid
- Assuming the phone system is the only thing affected.
- Leaving it until your line provider schedules the migration for you.
- Cancelling old lines before numbers have ported.
- Moving voice onto a connection that already struggles at busy times.
How Omega IT can help
We audit lines and devices, plan the move and provide Hypercloud Voice, our hosted phone system, with number porting handled for you. Get a business phone quote or read our step-by-step guide to moving your business phones to hosted VoIP.