What porting actually is
Porting moves a UK phone number from one provider to another while the number itself stays the same. You keep the digits; only the network routing behind them changes. It applies to landline numbers moving to a cloud service, so a number that's been on a BT line for twenty years can end up ringing a mobile app.
What you'll need to hand
- a recent bill from your current provider, showing the account number and the exact billing address
- the full number, or the range of numbers, you want to move
- the name the account is registered in — mismatches are the most common cause of a rejected port
How long it takes
A single geographic number typically completes in around two weeks from the request, though simple ports can be quicker and multi-number or multi-site ports take longer. You agree a porting date in advance, and the switch itself happens within a short window on that day.
The cutover window — the bit nobody tells you
Be straight with yourself about switch day: a port is a handover between two networks, and there is a short period when the number has left the losing provider but isn't yet live on the new one. During that gap callers may hear a fault tone or nothing at all. It's usually minutes rather than hours, but it isn't zero, and any provider promising a completely seamless port is overselling it.
Keeping the gap harmless
- Don't cancel your old service first. Cancelling releases the number and you may lose it for good. Keep the line active until the port completes; the old provider closes it afterwards.
- Go live before the port. Set the new system up on a temporary number so everything is tested and the team is trained before the real number moves.
- Advertise a mobile for the day. Put a mobile number on your site, Google profile and voicemail greeting for switch day so anyone who can't get through has somewhere to go.
- Pick a quiet slot. Mid-week mornings are usually calmer than a Friday afternoon.
When a port can be refused
The usual reasons are administrative: the account details don't match, there's an outstanding balance, the number is inside a range that can't be split, or a port has already been requested. Most are fixed with the correct bill in front of you and re-submitting.
Do it before the switch-off
Analogue lines are being retired, so numbers will need to move to a digital service anyway. Planning it now beats being moved on someone else's timetable — see our PSTN replacement guide and switching from BT.
Next steps
Once the number's sorted, the setup itself is quick — see how a virtual landline works.