Guide
Keep Your Number:
Porting to VoIP Explained
Keep your number when you change provider: what Ofcom requires, the Letter of Authority, how long a UK port takes, why ports fail, and how to avoid downtime.
By the AymexConnect team, Aymex LTDUpdated Published
In short
Porting moves your existing UK phone number from one provider to another, so customers keep dialling the same number. Under Ofcom's General Conditions every UK provider must support porting and cannot refuse without good reason. You give the new provider the number, your current account details and a signed Letter of Authority; they raise the port, and the number switches over on an agreed date, usually within one to two weeks for a single geographic number. Your old line keeps working until then.
Your right to port
Ofcom's General Conditions of Entitlement require UK communications providers to port numbers on request, and the losing provider may not refuse except for defined reasons such as a mismatch in account details or an outstanding contractual term. You do not need the losing provider's permission; you need their cooperation, which the rules oblige them to give.
Geographic numbers (01 and 02), non-geographic numbers (03, 08) and UK mobile numbers can all be ported, though each follows a different process and the mobile process (PAC codes) is faster.
What you need to hand
- The numbers to move, including any ranges (for example 0207 123 4500 to 4599) and whether each is a single line, a multi-line or an ISDN DDI range.
- The current provider's name and your account number with them.
- The exact business name and installation address held on that account. Most rejected ports are rejected because these do not match.
- A signed Letter of Authority (LOA): a one-page form naming the numbers and authorising the new provider to act. Your new provider supplies it.
- A copy of a recent bill, which some losing providers ask for to confirm the account.
The timeline
| Port type | Typical time once accepted | Notes |
|---|---|---|
| Single geographic number | 7 to 10 working days | Can be quicker; depends on the losing provider's porting desk |
| Multi-line or DDI range | 2 to 4 weeks | Needs the whole range on one order; partial ranges are often rejected |
| ISDN30 ranges | 3 to 4 weeks | Coordinate with the PBX decommission so no calls are lost |
| UK mobile number | 1 working day with a PAC | Text PAC to 65075 to get the code from your current mobile provider |
These are industry norms rather than an Ofcom guarantee; Ofcom does not publish a maximum porting time for business fixed lines. If a port is rejected, the rejection reason tells you what to correct (usually the address or account number) and the port is resubmitted.
Avoiding a loss of service
- Do not cancel the old service first. Cancelling releases the number and it can be quarantined or lost. The port itself ends the old service for that number.
- Keep broadband separate. If your broadband is on the same line as the number being ported, tell both providers, or the port can cease the broadband.
- Set up the new system before the port date: users, ring groups, voicemail greetings and opening hours, so the number lands on a configured system.
- Use a temporary number during the overlap. A new provider can give you a fresh number on day one so you can test the apps and devices before your real number arrives.
- On the port day, make and receive a test call from every device and check the number displays correctly as caller ID.
How AymexConnect handles it
During the 30-day trial you get a UK number as soon as your business is verified, so you can test calls, SMS, voicemail and the apps before you move anything. When you are ready, send us the numbers and the LOA from the dashboard, we raise the port and tell you the committed date, and your current provider keeps working until then. There is no charge for porting a number in.
Questions people ask
Only for defined reasons such as mismatched account details or a number that is not theirs to release. Under Ofcom's General Conditions they cannot refuse simply because you are leaving. If they stall, the rejection or delay reason has to be stated, and unresolved complaints can go to the Communications Ombudsman or CISAS after eight weeks.
No. The port can go ahead, but you may still owe early-termination charges under your old contract. Check the end date before you set a port date.
Normally a few minutes while routing updates. Having the new system configured and a test number already in use removes most of the risk.
Usually yes, provided the name and address on the residential account match what you give the new provider. Tell them it is a residential line so the LOA is completed correctly.
Sources
Third-party facts on this page were read from the sources below on the date shown. Providers change prices and terms; check their site before you decide.
- Ofcom General Conditions of Entitlement (number portability) · checked 3 November 2026
- Expert Market: how to change landline provider and keep your number · checked 3 November 2026
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