26 October 2026

UK phone network switch-off: 5 steps for businesses

Prepare for the UK phone network switch-off with five checks to protect your numbers and calls, and know what to ask each provider before switching.

A modern Spanish office desk with a telephone and laptop, lit by daylight

If you serve customers in the UK, prepare for the UK phone network switch-off in five steps: list your numbers and lines, ask each provider which service is changing and when, check whether you can keep each number, decide who answers each call, and test both the usual call route and what happens if it fails before cancelling anything.

In short:

List the UK numbers you publish. Record which provider and line receive calls to each one.
Ask each provider for the timetable and changes affecting its service. Do not assume every line will change at the same time.
Check the UK number, call forwarding and phone system separately. Different providers may handle different parts of the same call.
Before cancelling a line, confirm how you will keep the number. Test what happens if your main connection fails.

The priority is not to buy another phone system. It is to know how each call reaches you today.

Which numbers and lines should a business inventory first?

A business serving the UK market should start by listing every number it publishes. For each one, identify the provider and trace the call to the line that receives it. Include any call forwarding and equipment connected to a fixed line in a UK office.

A UK number does not mean the business has a physical line there. The call could be forwarded to a line in Spain. To check, make a record for each number:

Where it appears: on the website, in contracts or in email signatures.
Who provides the number and who bills for the line that receives the call.
Where the call ends up and which forwarding rules are active.
Which phones or other equipment depend on a UK fixed line.

If you use virtual numbers for businesses, distinguish between the provider of the number and the provider that delivers the call. Then you can ask each provider about the service it handles.

How can you confirm whether the network change affects each service?

Ask each provider to confirm in writing what technology carries the calls it delivers, which service it plans to change, when the change will happen and what action you need to take. The number a customer sees does not, on its own, tell you which network carries the call.

If one provider supplies the UK number and another receives the forwarded calls, ask both. Have them distinguish between the service associated with the number, the line carrying the call and the forwarding destination. A general answer about “your number” does not tell you which part of the call route will change.

Ask for each service identifier, the date that applies to it and who is responsible for each task. Keep the answers with your inventory. Before replacing your cloud PBX because of a general notice, check its scope with each provider. To organise that review, see how to review a small business’s phone services.

What should you check before changing a number or provider?

Before changing a UK number or its provider, get written confirmation of who holds the number, whether you can keep it, which call forwards are still active, how calls will be routed during the change, and when you can cancel the old line without missing calls from customers in the UK.

Ask both your current and new providers before starting the change:

Ownership: check that the name on the contract matches the registered holder of the number.
Number retention: get confirmation that the new provider can take on the UK number, and ask what conditions apply.
Call forwarding and cancellation: find out who manages each call forward. Do not cancel the old line until you have tested the new call route.

You can use this guide to prepare a number port, but do not assume its timelines apply in the UK. Confirm the process with the providers involved.

How should you handle calls in the new setup?

To handle calls from the UK, decide who receives each type of enquiry and when they are available. Set out how calls are routed when the team is busy, where they go if nobody answers, and how an enquiry can be transferred without relying on a single line.

Before configuring the service, review the cloud PBX features and write down these rules:

Opening hours: state when the team answers calls and what happens outside those hours.
Extension: give each person or department an internal destination for receiving and transferring calls.
Queue: decide where calls wait when everyone is busy.
Call forwarding: set an alternative destination for unanswered calls.

Confirm who can change these rules and who follows up on enquiries that go unanswered.

What should you test before disconnecting the old line?

Before disconnecting the old line, call every published number from the UK. Check caller ID, the call queue, forwarding and what happens when the main connection fails. Record the results. Agree with the provider when to disconnect the old line only after both the normal and backup routes have passed the tests.

Run the tests with the people who will answer the calls. Check what happens when a caller waits in the queue, nobody answers or a call comes in outside business hours. If the team relies on the office’s fibre and mobile connection, test the backup route with the main connection disconnected.

For each attempt, note the number dialled, where the call came from, who received it and what failed. Send the log to the provider and ask them to confirm when to disconnect the old line. A planned configuration does not guarantee continuity. It has to work in the test.

Frequently asked questions

Will my UK number stop working if my team answers calls from Spain?

Not necessarily. Answering from Spain does not determine whether your UK number stays active. What matters is how your provider receives the call and routes it to your team. Ask which service supports the number, whether a call forward is involved and what will change in that route. Do not cancel a line just because of where your team answers calls.

Will this change affect calls I make from Spain to the UK?

A change to a UK line does not, by itself, stop you calling the UK from Spain. Your outgoing call and the service used by the person you are calling are separate. If a destination number becomes unavailable, that call may fail. If you encounter problems, ask your provider to investigate and identify the affected numbers.

Can I keep my UK number if I change providers?

Possibly, but do not assume you can. It depends on the type of number, the providers involved and the applicable conditions. Before requesting the switch, get written confirmation that the new provider can receive calls to that number. Ask what will happen to any active call forwards. Agree on the transition before cancelling your current service.

Do I need to replace phones or equipment in a UK office?

Not always. It depends on which line each device uses and whether that service will change. Check alarms, terminals and any other devices connected to the line, not just phones. Ask your provider to identify the affected connections and confirm which devices will keep working. Test each use before disconnecting the old service.

What should I ask my provider if my UK number forwards calls to a mobile?

Ask who maintains the number, which service handles the call forward and whether that service will change. Confirm what happens when the mobile is busy, switched off or out of coverage. Get the charges for forwarding in writing. Test the call route before changing it. Request a demonstration to review how your team will answer calls from UK customers.

Request a cloud PBX demonstration and review how your team will answer calls from UK customers.

Written by Mehdi Chouikh, CEO.