Changing network is quicker than most people expect. Your new provider does most of the work, and Ofcom’s rules mean you pay only one provider during the changeover. This guide covers what to do before, during and after, what leaving can cost, and how to protect your number from fraud.
Before you start
- Check your phone is unlocked. Providers can no longer supply locked handsets, but an older phone may still be tied to its first network.
- Back up your phone, and move any authenticator apps over before you change SIM.
- Decide whether to keep your number. If you keep it, apps tied to it carry on working. If you take a new one, update your bank, delivery apps and messaging apps.
- Find out what it costs to leave, using the checks in the next section.
- Pick the new plan and make sure the new network works where you live. See picking a network before you move and poor signal as a reason to move.
Making the move
- Choose your new plan and order the SIM or eSIM. A new plan to switch to is easy to find on our comparison.
- From the SIM you want to keep, text PAC, free, to 65075. Your provider must reply within about a minute. You can also request it from your online account.
- The reply carries your 30 day switching code, together with any leaving charges or pay as you go balance.
- Give the code to your new provider when you order. It must complete the switch within one working day.
- Your old account closes when the number moves, so you do not need to cancel it yourself.
If you want a new number, text STAC to 75075 instead and follow the same steps. To check whether you are still in contract without starting a switch, text INFO to 85075.
Some providers set cut off times, for example a switch requested before 5pm on a weekday goes through the next working day. If you hold several numbers on one account, such as a family plan, you must request codes online or by phone, not by text.
If you cancel first and then change your mind about the number, you can still ask your new provider to keep your old number for free, as long as you ask within one month of cancelling.
eSIM switches
Activate the new provider’s eSIM first. It will have a temporary number. Then enter your switching code in the provider’s account page or app, and your old number replaces the temporary one. Ending the old service is part of that step. Our guide to setting up an eSIM when you switch covers the phone side.
Moving from a physical SIM to an eSIM with the same provider does not use a switching code. A code is only for moving between providers, so ask your current provider how to move within its own plans.
What leaving can cost
| Your situation | What to expect |
|---|---|
| Out of contract | No leaving charge. Notice periods after the switch date are banned. |
| In a fixed term SIM only plan | Usually the remaining monthly payments. The reply to your text shows the exact figure. |
| In a phone contract | The remaining payments, including the phone. See what leaving a handset contract costs. |
| Pay as you go | Use up your balance first, since it may not be refunded. See moving a pay as you go number. |
| Your price has gone up beyond your contract | You can leave without a fee within 30 days of the notice. See leaving without a fee after a rise. |
If you are weighing a new phone as well, consider staying put and upgrading instead.
Keep your number safe
Your switching code lets someone move your number, so treat it like a password. Criminals use SIM swap and port out fraud to take over a number, then use it to get one time codes for bank and email accounts. Cifas reports that unauthorised SIM swap cases rose 38% in 2025.
Warning signs include an unexpected message about a SIM or switching code, or sudden loss of service. If that happens, call your provider straight away, tell your bank, and consider reporting it to Cifas. To reduce the risk:
- Do not share your code with anyone who contacts you.
- Keep personal details such as your date of birth off social media.
- Use an authenticator app or passkey instead of text messages where you can.
- Turn on any extra security your provider offers for your account.
If it goes wrong
Your service should not be off for more than one working day during a switch. If it is, or if your provider misuses the process, you are entitled to reasonable compensation. Your provider must give you your code if you ask. If it will not, complain to it in writing, and take the case to the communications ombudsman after eight weeks.
FAQs
Can I get a code while I am abroad?
Often not by text. Many providers need you to be in the UK, and the text service can fail on roaming. Use your online account if you can, or wait until you are back.
Do I need a code for a new SIM on the same network?
No. A switching code is for moving between providers. For a new SIM or eSIM from the same one, contact your provider.
What if my provider will not give me a code?
Ask again through its online account, then send a written complaint. The ombudsman route opens after eight weeks, and Ofcom wants to hear about patterns of problems.