Switching mobile network takes one free text, and the network you are leaving is not allowed to talk you out of it. Since July 2019 the whole process has run under Ofcom's rules. Your switching code must arrive within one minute, the switch must complete within one working day, and your old network cannot bill you for a notice period that runs past the switch date. This guide covers the three text codes, what happens to your number, your signal and your credit, and exactly what your old network can and cannot do on the way out.
Which code do you text?
Everything starts with a free text from the phone you want to switch. There are three codes, and picking the right one matters.
- PAC (Porting Authorisation Code): text PAC to 65075 to leave and take your number with you. This is the one most people want.
- STAC (Service Termination Authorisation Code): text STAC to 75075 to leave and start fresh with a new number.
- INFO: text INFO to 85075 to see your contract end date and what leaving would cost. It commits you to nothing.
Requesting a code is free and does not end your contract by itself. Nothing happens until you hand the code to a new network, so if you change your mind you can simply let it expire. The full process is set out in Ofcom's guide to switching mobile provider.
Keep your number: the three steps
- Text PAC to 65075. The reply must arrive within one minute, and it contains more than the code. Your network has to include what Ofcom calls switching information: any early termination charge, and any pay as you go credit you would lose. Everything you need to decide is in one message.
- Pick your new deal and hand over the code. Every network asks for it during sign-up, online or in store. If you have not chosen yet, start with our SIM only comparison and check the signal at your address on our UK mobile coverage map first.
- The new network does the rest. The switch must complete within one working day of your code being accepted. Your old contract ends automatically. There is nobody to phone and no retention script to sit through.
Your PAC stays valid for 30 days. If it expires before you use it, nothing is lost; text 65075 again and a fresh code arrives within a minute.
Leaving without keeping your number
A STAC works exactly the same way, except your old number is retired instead of ported. Text STAC to 75075, give the code to your new network, and the old contract ends within one working day of the code being accepted.
A fresh number makes sense less often than people think, but it has its uses: escaping years of nuisance calls, separating a work number from a personal one, or simply drawing a line. If you are in any doubt, keep your number. Banks, NHS logins and two-step verification all lean on it.
Check what leaving costs first
Before you request either code, text INFO to 85075. The reply shows your contract end date and any early termination charge, straight from your network's own systems, and it triggers nothing. Treat it as your evidence.
One situation changes the maths entirely. If your network has raised prices beyond what your contract set out in pounds and pence, you may have the right to leave without paying the termination charge at all. Our guide to SIM only mid-contract price rises explains exactly when that right applies and how to use it.
What your old network is not allowed to do
The switching rules sit in Ofcom's General Conditions, and they put every obligation on the networks rather than on you. Your old network must:
- Send your PAC or STAC, with the switching information, within one minute of your text.
- Complete its side of the switch so you are moved within one working day.
- Stop billing you from the switch date. Charging for a notice period that runs on after you have left was banned in July 2019, a change Ofcom estimated would save UK mobile customers around £10m a year.
- Compensate you if the switch fails or is delayed through its error.
- Sell phones unlocked. Any handset bought from a UK network since December 2021 works on every other UK network.
What it cannot do is refuse the code, delay it, or make you sit through a retention call. Persuasion is allowed only if you phone them; the text route bypasses it entirely. If a network obstructs a switch, that is a rule breach worth escalating, and our complaints guide shows the path.
Will you lose signal during the switch?
Under the rules, any loss of service must not exceed one working day. In practice most ports complete in a few hours, and many in minutes; the old SIM stops working and the new one picks up your number.
Worried about your data? Almost nothing else moves, because almost nothing else needs to. Contacts, photos and WhatsApp chats live on your phone or its cloud backup, not on the SIM, so they are untouched by the switch. The one genuine loss is voicemail: messages saved on your old network's system do not transfer, so listen to anything important before the switch completes.
On pay as you go? Spend your credit first
Pay as you go numbers port exactly the same way, and with no minimum term there is no exit fee to worry about. The catch is your credit. Any remaining balance does not follow you to the new network, and the PAC reply must state the amount you would lose. Run it down before you switch, or ask your network whether it offers a refund; a few do, most do not.
Before you switch: a two-minute checklist
Five small checks now save the only headaches this process can produce. None of them takes longer than the kettle.
- Check the new network's signal at your address. Coverage maps flatter everyone, so check independently: Ofcom's mobile coverage checker shows every network at your postcode.
- Text INFO to 85075. Know your exit charge before the new network asks for your code, not after.
- Listen to saved voicemails. They are deleted when the old account closes.
- On pay as you go, run your credit down. The balance does not move with you.
- Old handset going to a new SIM? If it was bought before December 2021 it may still be locked; ask your current network to unlock it, which must be done free of charge.
Switching with an eSIM
More plans are now sold on eSIMs than ever, and the switching rules are identical. You text the same codes, the port still completes within one working day, and the only difference is delivery: the new network issues your eSIM digitally, so there is no envelope to wait for. If your phone supports it, an eSIM switch can be the fastest route of all.
One practical note if you are staying on the same phone. Moving an eSIM between networks means the new network issues a fresh eSIM profile rather than transferring the old one, so follow its set-up steps rather than your phone's transfer tool. Moving to a new phone as well? Set the phone up first, then activate the new eSIM on it.
Already cancelled? You have a month
Cancelled your contract and then realised you wanted the old number? You can still request a PAC within one month of cancelling, free of charge, and take the number to a new network. After that window the number goes back into the pool, so move quickly.