PAC Code: How to Get One and Keep Your Number When You Switch
A PAC code is the nine-character code that lets you take your mobile number with you when you switch networks. To get one, text PAC to 65075 from the phone you want to keep. Your network has to send it back within a minute, it costs nothing, and it stays valid for 30 days. Hand it to the network you are joining and the number moves, usually within one working day. That is the whole process. The rest of this guide covers the parts that catch people out — the timing traps, and what to do when your bank’s security texts stop arriving mid-switch.
The 30-second version: Text PAC to 65075 → you get a nine-character code within about a minute → give it to your new network when you order → your number moves in about a day. Free, and you never have to phone anyone.
What is a PAC code?
PAC stands for porting authorisation code, and you will also see it called a PAC number. It is your permission slip: it proves to the receiving network that you are entitled to move that number. In practice, here is what you are dealing with:
- Nine characters, a mix of letters and numbers
- Tied to one specific number — you cannot use it for a different line
- Free, on every network, every time
- Valid for a 30-day window from the moment it is issued
- Closes your old account automatically once it is used
You need one because number porting exists: a mobile number does not belong to a network. Ofcom allocates ranges of numbers to providers, but the right to keep using a number follows you rather than staying with the company that issued it. The code is simply the mechanism that lets you exercise that right.
One thing worth understanding before you start: handing over the code also closes your old account automatically. You do not need to ring your old network to cancel, and you should not, because doing both can confuse the process.
How to request a PAC code
There are three ways to request a PAC code, and the first is by far the easiest. All of them are free, and all work whichever mobile network you are on.
The text method — works on every UK network
- From the phone holding the number you want to keep, text the word PAC to 65075. This is the same shortcode on every mobile network, though some have their own quirks — if nothing comes back on O2, the O2 PAC code guide covers the three blocks that cause it.
- Your code arrives by text. Under Ofcom’s text-to-switch rules every network must send it within a minute, and in practice that is what happens. The other routes are slower: ask by phone and it must come immediately or by text within two hours, while an online request can legitimately take up to two working days. If you are in a hurry, text.
- The text also tells you any outstanding charges you owe, such as a handset balance or early exit fee.
If texting is not an option, you have two alternatives:
- Your online account or app — usually filed under account settings or a “leaving us” section
- Customer services — works, but expect a retention offer. The text method exists precisely so you can skip that conversation
If you have been wondering how to get a PAC code without speaking to anyone at all, the text route is the answer. Whichever route you take, the network cannot refuse or delay the code as a way of keeping you.
Text from the right phone. The request has to come from the number you are moving. If that SIM is broken, lost, or in a drawer, you will have to use the app or call instead.
How to use the code once you have it
Give it to the network you are joining, not the one you are leaving. Most ask for it during sign-up, so you can enter it as you place the order. If you have already ordered, there is normally a form in your new account, or you can give it when your SIM arrives.
Have these ready before you begin:
- The code itself, exactly as it was sent to you
- The number you are transferring
- Account details that match your old network’s records — name, address and date of birth
Mismatched details are the single most common reason a switch fails. Check what your old network actually holds rather than assuming, especially if you have moved house or the account was set up years ago.
The code lasts 30 days. Nothing happens to your service while it sits unused, and requesting one does not commit you to anything — you can ask for a code, change your mind, and simply let it expire.
What happens on the day you transfer your number
Transfers normally complete within one working day of the request being submitted. There is a timing detail most guides skip: if you hand the code over late in the afternoon or in the evening, the clock effectively starts the next morning, which pushes completion into a second day. Weekends and bank holidays do not count either.
| Stage | What you notice |
|---|---|
| Before the switch | Old SIM works normally. New SIM has a temporary number, if it has service at all. |
| Cut-over | Old SIM loses service. This is the moment the transfer happens. |
| Immediately after | New SIM picks up your number. Restart the phone if it does not appear. |
| First few hours | Calls and texts settle. Incoming texts are usually the last thing to start working. |
A short gap in service on the day is normal and expected. A gap lasting days is not, and that is covered further down.
Before you start: protect the accounts tied to your number
This is the step almost nobody tells you about, and it is the one that causes real damage when a switch goes wrong.
Your mobile number is probably the recovery route for your bank, your email and your work logins. If incoming texts stop arriving mid-transfer — which happens more often than the official guides suggest — you can find yourself locked out of accounts that use two-factor authentication by SMS, at exactly the moment you cannot receive the codes to get back in. UK network forums are full of people stuck in this position for weeks, including one NHS worker unable to reach work systems during an extended port.
Do this before you request the code, not after:
- Switch critical accounts from SMS codes to an authenticator app — banking and email first
- Add a backup email or recovery method that does not depend on your phone number
- Write down your bank’s phone number so you can reach them if you are locked out
- Check whether your work login uses SMS two-factor authentication, and sort it before you switch
Doing this takes ten minutes and turns a potential crisis into an inconvenience. It is worth it even if your switch goes perfectly.
PAC code or STAC code — which do you need?
Two codes, two very different outcomes, and picking the wrong one is one of the few genuine ways to lose a number for good.
| You want to | Ask for | Text |
|---|---|---|
| Move to a new network and keep your number | PAC | PAC to that shortcode |
| Leave and give up the number entirely | STAC | STAC to 75075 |
Both are free and both close your old account. The difference is that a STAC code releases the number rather than moving it. If you are unsure, ask for the PAC — you can always drop a number later, but you cannot get one back once it has gone.
If you are moving specifically to hold on to a number worth keeping, the PAC is also what a dealer will ask you to use when transferring a premium mobile number into your name. Buying one is the only way to pick your own mobile number, since no UK network lets you select the digits.
When a switch goes wrong
Most people switching networks never hit a problem. When something does go wrong, the pattern is usually one of these, and knowing which one you have tells you what to do.
Your new SIM has no service after the cut-over
Restart the phone first — this fixes it more often than anything else. If there is still nothing after a couple of hours, contact the network you have joined, because once the request is submitted they control the process. Your old network can no longer help.
Calls work but texts do not
This is common and genuinely frustrating, because the texts that fail first are often the automated ones from banks and security systems. It is a routing problem at the network end, not something on your handset. Report it as a routing or SMS delivery fault specifically, rather than as “no service”, because that description gets it to the right team faster.
The old SIM is still receiving your calls
The transfer has not completed, whatever either network has told you. Do not throw the old SIM away until the new one has been working normally for several days.
Nothing has happened for over a week
Ports have been known to stall for weeks. At this point stop calling repeatedly and put a formal complaint in writing with the receiving network, keeping a record of dates and reference numbers. If it is not resolved within eight weeks, or you receive a deadlock letter, you can escalate free of charge to an alternative dispute resolution scheme — every UK provider must belong to one, and the regulator publishes which scheme covers which company.
Common questions
Does a PAC code cost anything?
No. Networks must issue one free of charge. You may still owe money on your account — a handset balance or early termination fee — but that is separate from the code itself.
What if my code expires?
Request another one the same way. There is no limit and no penalty for letting one lapse.
Can I get one on pay as you go?
Yes. The process is identical on pay as you go and pay monthly. Any credit left on a prepaid account does not transfer, so spend it first.
Will I lose my contacts or messages?
Contacts stored on the phone or in a cloud account are unaffected. Anything saved to the physical SIM stays on that SIM, so copy it across before you swap.
Does an eSIM change anything?
The porting process is the same, but activation depends on your new provider issuing a QR code or activation profile. Keep the old physical SIM available until the transfer has settled.
The short version
Text PAC to the shortcode, give the code to whoever you are joining, and expect your number to arrive within a working day. That covers the overwhelming majority of switches, and it costs nothing.
The two things worth doing beyond that are small. Move your critical accounts off SMS codes before you start, so a delay cannot lock you out of your bank. And keep the old SIM until the new one has behaved normally for a few days, because a transfer that looks finished is not always finished. Get those right and the worst case is a slow switch rather than a genuine problem.
Sources
- Ofcom — Switching mobile provider, on the text-to-switch rules, free issuing of codes and provider obligations.
- Porting Authorisation Code, on the nine-character format, the two working hour issuing requirement and 30-day validity.
- SMARTY — PAC code or STAC code, on the difference between the two codes and when each applies.
- 5G.co.uk — PAC codes guide, on transfer timing and the late-in-the-day delay.
Last reviewed 5 September 2026. Switching rules and network processes change; this guide is re-checked when they do.
