PSTN Switch-Off Checklist: Is Your Business Ready for 2027?

By Olivia Johnson - Trusted UK Business Expert

Last Updated 2nd of October 2026

7 minute read

The UK phone network is changing, but your move does not need to be hard. This clear PSTN switch-off checklist will help you find every affected service, choose safe replacements and move before the deadline with less risk.

To be ready for the PSTN switch-off, audit every phone line and connected device, choose an IP replacement, check broadband and backup power, test all services, train staff, update emergency plans and complete the move before 31 January 2027.

A phone-system upgrade alone may not protect your business. Read on to find hidden lines, plan the right tests and use a practical checklist that takes you from discovery to a safe digital service.

The PSTN switch-off is changing how UK businesses use landline services. Make sure your business is prepared for the move to digital phone systems.

Click the link below to check your options and prepare your business for the PSTN switch-off.

PSTN Switch-Off Checklist: Is Your Business Ready for 2027?

The Public Switched Telephone Network, or PSTN, is the old UK phone network. It uses analogue equipment and copper phone lines. BT plans to retire it on 31 January 2027. Ofcom says providers that use BT’s network must follow the same timetable, while firms with their own networks plan a similar move. This is an industry change, not a ban made by Ofcom or the Government.

Calls will move to digital technology called Voice over Internet Protocol, or VoIP. A digital call travels through an internet connection. ISDN services are also affected. Your phone number may stay the same, but the way the call reaches you will change.

The biggest mistake is to count only handsets. Traditional lines often support fire and burglar alarms, lift emergency phones, door entry units, fax machines, payment terminals, franking machines, CCTV, intercoms, building controls, telecare, modems and remote monitoring. A quiet line in a plant room can be more vital than the main office number.

Use this checklist for every site:

• Name one project owner and one senior sponsor.
• List every PSTN, ISDN and broadband service on bills.
• Trace each number and socket to a device, site and business use.
• Ask facilities, finance, IT, security and site teams about hidden lines.
• Mark safety, legal and customer-critical services first.
• Contact each device maker, maintainer and monitoring centre.
• Get written proof that the proposed service is supported over IP.
• Check broadband speed, stability, capacity and coverage.
• Plan backup power and a second connection where downtime is unsafe.
• Choose VoIP, cloud calling, SIP or another approved replacement.
• Confirm number porting, call flows, recordings and emergency-call details.
• Run a pilot, including power and broadband failure tests.
• Train staff and update guides, contracts and continuity plans.
• Remove old lines only after full testing and sign-off.

Create a register rather than relying on memory. For each line, record its number, provider, bill reference, address, socket, device, owner, supplier, risk rating, replacement, test result and closure date. Add contract end dates and notice terms. This record stops duplicate costs and gives leaders clear proof of progress.

Do not assume an adapter makes every old device safe. An analogue telephone adapter can let some equipment connect to an IP service, but alarms and data devices may use tones, timing or signalling that do not pass well through VoIP. Ask the device supplier to approve the full setup. If the answer is unclear, replace or test the device under real conditions.

Power is another major change. A classic corded PSTN phone often worked during a local power cut because the exchange supplied power. A router, IP handset, Wi-Fi point and network switch need power at your site. A battery unit may keep them on for a time, but its size must match the risk. Know what must work, for how long and who checks the battery.

Your business is ready only when every legacy line has a named outcome: migrate, replace or close. Orders are complete, important numbers are ported, users are trained, failure tests have passed and suppliers have accepted responsibility. A quote or planned date is not readiness. Working evidence is.

Which Business Services Will the Switch-Off Affect?

Begin with bills, but do not end there. Bills may show numbers without explaining their use. Walk each site and follow wall sockets and cables. Speak with people who know the building. An engineer, caretaker or long-serving office manager may remember a line that is absent from the IT list.

Use a simple risk table:

Give the highest priority to anything that protects life, property, money or a legal duty. A failed sales phone is harmful, but a failed lift alarm can put a person at risk. Your risk score should consider impact, not just how often the line is used.

Check numbers used in adverts, vans, signs, websites and customer records. Plan number porting early so callers still reach you. Map opening messages, hunt groups, voicemail, call recording and contact-centre links. Confirm where emergency services will send help when a user dials 999 from each site or softphone.

Also review privacy and security. Cloud call services hold account data and may store recordings. Ask where data is kept, who can access it, how long it is retained and whether strong sign-in controls are available. Limit admin rights, use multi-factor authentication and keep software current. The new system should meet your data rules, not weaken them.

How Should You Plan, Test and Complete the Move?

Work backwards from 31 January 2027, but set your own finish date much earlier. Allow time for site surveys, fibre orders, hardware delivery, number ports, supplier visits, staff training and fixes. Large or multi-site firms should move in waves. Start with a normal site, learn from it, then handle complex and high-risk places.

Choose the replacement by need. Cloud calling suits many firms because the provider runs the main platform and users can call from phones, computers or mobiles. SIP can connect an IP service to a suitable office phone system. Some small sites may use a digital voice service through a router. Special devices may need a new IP unit, mobile connection or monitored radio path. There is no single right answer for every line.

Compare Hosted VoIP vs On-Premise VoIP before deciding how your new phone system should be managed.

Check the network before adding calls. Measure internet use at busy times. Review router, firewall, switches, Wi-Fi, cabling and Quality of Service settings. Ask what happens if the main broadband link fails. A second line should take a separate physical route where one cable cut could stop both. Mobile backup can help, but first check signal inside the building and during local busy periods.

Review the best UK VoIP providers before choosing a service for your business.

Test the whole journey, not just the dial tone. Make and receive calls from outside. Test transfers, menus, queues, voicemail, call recording, caller display and emergency calls under your provider’s safe test process. Trigger alarms with the monitoring centre aware. Test lift units with the maintainer present. Confirm that the right site name, alert and return path arrive at the far end.

Then test failure:

• Remove main power and time how long key services stay live.
• Stop the main broadband link and confirm failover works.
• Restart the router and check that devices reconnect by themselves.
• Test an out-of-hours alert and the staff response.
• Record results, faults, fixes, owner and retest date.

Keep the old and new systems side by side for a short, controlled period where possible. Do not cancel a line merely because the new device lights up. Get sign-off from the service owner and, for alarms or lifts, the expert supplier or monitoring firm. Check one final bill after closure to catch lines that stayed active or charges that continued.

Train people in simple tasks: making and moving calls, using voicemail, reporting a fault and calling during an outage. Give reception and site teams a short printed guide. Update business continuity plans, supplier contacts and staff call trees. Schedule checks for batteries, backup links, user access and emergency location data.

What Are the Main Risks, Costs and Benefits?

The first risk is loss of service. The second is false confidence: a device may work in a quick test yet fail during a power cut, weak mobile signal or real alarm event. The third is delay. A late project may face limited engineer time, rushed choices and weak testing.

Build a full cost view. See the typical VoIP cost for a small business in the UK when planning your new phone budget. Include setup fees, handsets, adapters, cabling, licences, broadband, mobile backup, batteries, support, training and early contract charges. Then subtract old line rental, maintenance and unused services. Compare three-year costs, not just the first monthly price. Cheap service with poor support can cost far more after one serious outage. You can also check whether VoIP is cheaper than a business landline when comparing long-term costs.

Ask each supplier clear questions:

• Is this exact device and service supported after the PSTN closure?
• Who owns testing across the device, network and monitoring centre?
• What service level and repair time apply?
• What happens during a power or internet failure?
• Can we keep our numbers, call flows and recordings?
• How are security, updates, data and admin access managed?
• What evidence and support will you give after launch?

Digital calling can join desk phones, laptops and mobiles. It may also add call menus, reports, recordings and customer-system links.

The move should be treated as a business change, not a simple phone swap. Set dates, owners and approval steps for each site. Keep written test results for calls, alarms, lifts and backup power. Review the plan after each move, fix any gaps, and do not close an old line until its replacement has passed every check.

Do not wait for a hidden line to fail. Use this checklist, name your project owner and book a full PSTN readiness review today. Click the link below to plan your safe move to digital services before 2027.

Start your PSTN switch-off readiness review.

FAQ

When will the UK PSTN switch off?

BT plans to retire its PSTN on 31 January 2027. Providers using BT’s network must work to that timetable, and other network firms plan similar changes. Set an earlier internal finish date so there is time to test and fix faults.

Will my current desk phone still work?

It may work through a router or adapter, but this depends on the phone and service. IP handsets connect directly to a digital network. Ask your provider what is supported, and test every key feature before the old line closes.

Will digital phones work in a power cut?

Not unless the router, phone and network equipment have power. Plan a battery, generator or other backup based on how long the service must run. Keep a charged mobile option where suitable and test the plan often.

Does the switch-off affect alarms and lifts?

Yes, it can. Many alarms, lift phones, door systems and monitoring units use an analogue line. Contact the equipment maker and monitoring firm. Use an approved replacement and test the complete alert route, including power failure.

Can my business keep its phone numbers?

Usually, numbers can be moved to a new provider or digital service, but porting needs care. Check every number, address and account detail early. Keep the old service active until calls route correctly and the business owner signs off.

Prepare Your Business for Life After PSTN.

Still using a PSTN phone line? Now is the time to review your business phone setup and explore modern alternatives such as VoIP.

Click the button below to compare business phone options and get ready for the PSTN switch-off.