Phone Number Porting UK: How to Keep Your Number When You Switch VoIP Provider
Changing phone providers used to mean changing your number. For a consumer, that is an inconvenience. For a business, it can be a serious problem. Your number is printed on business cards, listed on your website, embedded in Google Maps, referenced in email signatures, on vans, on signage, and in the heads of every customer who has ever called you. You cannot simply issue a correction and move on.
The good news is that in the UK, you do not have to. Phone number porting — the process of moving an existing number from one provider to another — is a legal right protected by Ofcom regulations. You own the right to use that number. Your current provider cannot hold it hostage.
This guide explains how porting works in practice, what you need to do, and what to expect at each stage.
What Phone Number Porting Actually Is
Number porting is the transfer of a phone number from a losing provider (your current one) to a gaining provider (the new one). The number itself does not change. The routing behind it does. Once the port is complete, calls to your number arrive at your new provider's infrastructure instead of the old one.
This applies whether you are moving from a traditional landline, a legacy ISDN system, or one hosted VoIP provider to another.
Which Numbers Can Be Ported
Geographic numbers (01 and 02 prefixes) — These are the most straightforward. The vast majority of UK geographic numbers are portable. If your business has a 01202 or 0207 number, you can almost certainly take it with you.
Mobile numbers — Portable. The UK mobile porting process is well established and typically fast.
03 numbers — Generally portable. These non-geographic numbers were introduced specifically to be inclusive and accessible, and porting support is broadly consistent.
08xx non-geographic numbers — This depends on the specific range. Some 084 and 087 numbers are portable; others are not. If you have one of these, it is worth checking with your new provider before assuming the port is possible.
0800 freephone numbers — Generally portable, but the process can be more complex. Revenue-sharing arrangements and the way these numbers are routed adds steps. It is doable, but allow more time.
Which Numbers Cannot Be Ported
There are genuine exceptions, though they are rare.
If a provider assigned you a number that you have only held for a short period — a few weeks, say — and the number was never previously associated with your business, some providers will not port it on the basis that it is still considered a freshly allocated number. This is an edge case.
Some very old analogue exchange numbers, particularly those associated with legacy infrastructure, may not be portable. It is uncommon, but it is worth checking before you make any decisions based on keeping such a number.
The Porting Process, Step by Step
1. Sign up with your new provider and request the port
You start the process with your gaining provider — in this case, VoIPninjas. When you sign up, you tell us you want to bring your number across. We initiate the port request on your behalf.
2. Provide the necessary details
To raise a port request, we need: the number or numbers you want to port, the name of your current provider (the losing provider), the name on the account with that provider, and in some cases an account reference number or authorisation code. Getting these details right matters — a mismatch on the account holder name is one of the most common causes of a port being rejected or delayed.
3. The gaining provider raises the request with the losing provider
We handle this coordination. The losing provider is contacted formally through the porting process. They are required under Ofcom rules to cooperate.
4. The losing provider releases the number
Ofcom sets timeframes here. For consumer numbers, the losing provider must release the number within one working day of a valid request. For business numbers, the timeframe is up to five working days. Providers who delay beyond these limits without good reason are in breach of their regulatory obligations.
5. A porting date is agreed
A specific date — and usually a time window — is set for the port to complete. You will know in advance when this is happening.
6. The number moves across
On the porting date, your number is transferred to your new provider's system. In practice, the switchover takes a matter of seconds. Callers experience no disruption. The number simply starts routing to your new system.
How Long Does It Take in Practice
For a straightforward business port, the end-to-end process typically takes between five and ten working days. This includes the time to raise the request, wait for the losing provider to process it, agree a porting date, and complete the transfer.
Complications can extend this. The most common issues are: incorrect account details supplied at the outset, a losing provider querying the request, or numbers on a more complex product type (such as a DDI range or a hosted service with multiple lines). None of these are insurmountable — they just add time. Starting the process as early as possible gives you a buffer.
Keep Your Old Service Running Until the Port Is Complete
This is important. Do not cancel your existing service before the port has completed. If you cancel first, the number may be deallocated, and once that happens, it is typically gone. You cannot port a number that no longer exists on the losing provider's system.
Run both services in parallel until you receive confirmation that the port is complete and calls are routing correctly through your new system. Once you have verified that, you can contact your old provider to close the account.
What VoIPninjas Does in This Process
When you sign up with VoIPninjas, we handle the coordination with your losing provider on your behalf. You give us the number details and account information, and we manage the request through to completion. You do not need to navigate the porting process yourself or contact your old provider directly to initiate the transfer.
All VoIPninjas plans support inbound porting of your existing numbers. The Samurai and Shogun plans include DDI numbers as standard, so once your number has ported across, it sits neatly within your new setup.
Common Questions and Misconceptions
"My contract with my old provider is still running. Does that mean I cannot port?"
No. You can port your number at any time, regardless of whether your current contract has ended. Porting does not require you to cancel your existing service first. You may still have contractual obligations to your old provider — an early termination fee, for example — but those are a separate commercial matter. The right to port the number is not contingent on your contract status.
"Will there be any downtime when the number switches?"
No, or as close to none as makes no difference. The porting switchover takes a few seconds on the agreed date. Callers are not sent to a dead tone. The transition is seamless.
"What if my old provider refuses to release the number?"
They cannot legally do so. Ofcom regulations require losing providers to cooperate with valid porting requests within the specified timeframes. If a provider is obstructing a port without grounds, that is a regulatory matter. In practice, providers comply — the system is well established, and most porting requests complete without any friction.
Ready to move your business number to a VoIP system that does not tie you into long contracts? VoIPninjas handles the porting process for you. Get started with a free 14-day trial — no card required, live within 10 working days. Start your free trial.
Frequently Asked Questions
Can I port a number that is currently on a PSTN or ISDN line?
Yes. Porting from traditional landline infrastructure to VoIP is one of the most common porting scenarios in the UK, particularly as the PSTN switch-off approaches in 2027. The process is the same — your new VoIP provider raises the request with your current telecoms provider, and the number is transferred to the hosted system.
What if I want to port multiple numbers at once?
Bulk porting is possible. If you have a DDI range or multiple standalone numbers, these can be ported as a batch. The process takes a little more coordination, but it is handled in the same way. Let VoIPninjas know the full list of numbers when you sign up and we will raise them together.
Do I need to give my old provider notice before porting?
You do not need to give notice in order to initiate a port. Your new provider raises the request directly. However, if your contract includes a notice period for cancellation, you should factor that in separately — it does not affect the port, but it affects when you can close the old account without incurring charges.
Will my number work exactly the same after porting?
Yes. To anyone calling you, nothing changes. The number is identical. On your end, calls arrive through your new VoIP system, which means you gain whatever features your new plan includes — call recording, auto-attendant, mobile app access, and so on — while keeping the number your customers already have.