PSTN switch-off: what your small business needs to check

What is actually being switched off?

The public switched telephone network, usually shortened to PSTN, is the traditional analogue telephone network. Its retirement also affects services built around legacy telephone lines, including older business telephone arrangements. Integrated Services Digital Network, or ISDN, is another older telephone technology being retired.

This is an industry-led replacement of ageing equipment. Ofcom sets regulatory requirements and the government has agreed migration safeguards with industry. It is not a government instruction to buy a particular package, and it does not mean every copper cable in the country disappears on the same morning.

That distinction matters if your premises cannot receive full fibre. A digital voice service can work over a suitable broadband connection that still uses copper for part of the route. The replacement must fit the services you use, rather than a label on a sales brochure.

Ask your provider to identify each product on your account in plain English. Is it a telephone service, a broadband connection, an equipment rental or a maintenance agreement? A bill containing several product names can make one physical line look like several separate services, or hide the fact that several business functions depend on one line.

Keep this inventory alongside the account number and the person authorised to make changes. If only an old director can approve an order, resolve that administration before booking technical work.

What the retirement date means for your business

The published retirement deadline is 31 January 2027. That is a programme date, not confirmation of the date on which your individual service will change. Your provider needs to tell you what is planned for your lines and equipment.

The wholesale network operator has announced a limited emergency voice-only transition service beginning on 1 February 2027 for remaining lines. Its purpose is a managed transition. It is not a reason to assume your existing broadband, alarm signalling or other connected equipment will continue unchanged. Get written confirmation for each use rather than treating the word emergency as a continuity guarantee.

National stop sell for the affected analogue products began on 5 September 2023. That means new orders and changes involving those products can bring migration forward. Stop sell is not itself the date existing equipment stops working. Moving premises, ordering an upgrade or changing provider can even so force you to address the replacement sooner.

If a salesperson says the deadline requires you to sign their contract, separate the two decisions. The network needs a migration. It does not follow that the proposed contract, equipment bundle or commitment period is the appropriate one for the business.

Request an order summary that distinguishes the network change from optional additions. Training, handset finance, call recording and maintenance should not arrive as an unexplained consequence of replacing the line.

Walk round the building before choosing a package

Start with the equipment, including things maintained by another company. The alarm panel in the corridor and the emergency telephone in a lift are easy to miss when the person organising broadband works entirely at a desk.

Do not unplug safety equipment to find out what happens. Record model details, photograph accessible labels and ask the maintenance firm to inspect where needed. A device accepting a telephone plug is not proof that a simple adapter will preserve every function.

For rented premises, ask the landlord which systems are shared. The lift telephone might be their responsibility while your intruder alarm is yours. Agree who places the order, who tests the replacement and who keeps the completion record. Otherwise both sides can reasonably believe the other has dealt with it.

Choose the connection and the phone service separately

Voice over Internet Protocol, or VoIP, means calls travel over an internet connection. The calling service might use desk handsets, computer software or mobile apps. Broadband supplies the connection; the telephone service supplies functions such as numbers, extensions and voicemail.

A connection-only broadband product may therefore be sufficient for the data link without including a telephone service at all. Conversely, paying for broadband does not prove that your existing business number has been transferred to a new calling platform.

Describe the working day before choosing features. Does the receptionist transfer calls to the workshop? Must several people answer the same number? Do staff work from home? What should happen when the office closes, or when nobody answers?

Write those requirements as actions and ask the specialist to demonstrate them. That is more useful than comparing long feature lists containing things your team will never use. Include the caller experience: the right greeting, a sensible ring pattern and a clear route to a person.

Our guide to SoGEA, full fibre and leased lines explains the connection choices. Availability, installation work and service performance depend on the premises, network and provider. Do not schedule a business-critical change solely around an estimated installation date.

Avoid moving an old dependency onto another old network

Replacing a telephone cable with a mobile signalling unit can be a suitable technical approach for some equipment. It still needs scrutiny. Ask which mobile generation the unit actually uses for its signalling, rather than which logo appears on the outer casing.

The UK is also moving away from older mobile networks. Government and parliamentary guidance describes the retirement of 2G and 3G, with an industry commitment to end those technologies by 2033. Individual network timetables differ. Equipment intended for a long service life needs a migration plan that accounts for those changes.

Ask the maintainer about current-generation connectivity, indoor reception, backup power and what happens if the preferred network is unavailable. A modern modem cannot compensate for an aerial installed where it receives no usable signal.

Treat compatibility as a written equipment decision. Record the model, signalling method and maintenance support, together with who confirmed that the proposed replacement meets the system's requirements. If the device reports to a monitoring centre, confirmation should include that end of the connection too.

The important question is whether the whole system works after migration. Replacing only the communication module may leave an older control panel, unsupported software or a separate power dependency unresolved.

Notice and backup power are different protections

The Fixed Telecoms Modernisation Charter contains voluntary commitments by signatories. These include at least 60 days' notice of a migration or closure affecting a direct customer, alongside engagement and alternative-technology commitments. Describe it as a charter commitment, not a universal statutory compensation scheme.

Ask your provider whether it is a signatory and how it applies the commitments to your account. Keep the notices. If you have already told the provider about an alarm or another critical dependency, ask for that information to be visible to the team carrying out the migration.

Digital equipment at your premises needs electricity. A battery arrangement for emergency calling is not automatically a business continuity system for broadband, handsets, network switches and payment equipment. Ofcom's emergency-access guidance and the government's migration checklist address safety; you still need a plan for trading during an outage.

A practical review follows the power chain. Identify the broadband termination equipment, router, network switch and handset. Ask which devices need an uninterruptible power supply, meaning a battery-backed electricity supply, and how long the proposed setup supports the actual load.

Then consider a separate route for calls and data. An automatic divert may help with incoming calls, but test how staff receive it. A mobile backup may help the connection, but confirm reception and whether the business applications work through it.

What to do next

Give one person responsibility for the migration record. They do not need to understand every cable. They need to know which supplier is responsible for each answer and whether the answer has been tested.

1. 1List all telephone numbers, line services and connected devices, including landlord-managed equipment.
2. 2Ask the provider to confirm the product, proposed replacement and migration arrangements for each line in writing.
3. 3Obtain compatibility and replacement instructions from the alarm, lift and payment-equipment maintainers.
4. 4Choose the data connection and calling service against the way the business actually works.
5. 5Agree number porting, meaning transfer to the new provider, before independently cancelling existing services.
6. 6Test normal operation and the agreed failure arrangements before signing off the change.

For the test, include incoming and outgoing calls, transfers, voicemail and the published main number. Let the relevant maintenance firms test safety and payment systems through their approved procedures. Do not make test calls to emergency services unless specifically arranged through an authorised process.

Keep the completion evidence with your service records, together with the provider's fault contact and the person who can authorise changes. A migration is finished when the business can use the replacement and knows how to get support, not simply when a new router arrives.