Switching your UK mobile network is far simpler than most people expect. Thanks to Ofcom's text-to-switch system, you can request a PAC code by sending a single text and transfer your existing number to any new network within one to two working days — no phone calls, no lengthy cancellation process.
This guide walks through every step, explains what a PAC code actually is, and covers the situations where you might not need one at all.
How to get your PAC code and switch networks
Send the word PAC (in capitals) from your current mobile number to 65075. This is free from any UK mobile, even if your phone is barred from making calls or you have no credit. You can also request it via your network's online account or by calling customer services.
Your PAC code will arrive by text within one working day — in practice most networks send it within a few minutes. The code is valid for 30 days, so you have plenty of time to shop around. Under Ofcom rules your network must also include your final estimated bill in the same message.
Before you commit, check what's available — prices vary significantly between networks. Use our comparison tool to find the cheapest SIM only deal for your data needs. Compare SIM only deals →
When you sign up with your new network — online or in store — there will be an option to keep your existing number. Enter your PAC code at this stage. Your new provider handles everything from here.
Your existing number moves to the new network, usually within one working day of your new SIM activating. You may experience a brief service interruption (typically overnight) while the transfer completes. Both your old and new network will text you to confirm when it's done.
What is a PAC code?
PAC stands for Porting Authorisation Code. It is a unique nine-character code (three letters followed by six digits) issued by your current network that proves you are the legitimate account holder and authorises the transfer of your mobile number to a new provider. Number portability — the ability to keep your number when switching networks — is a legal right in the UK, and the PAC system is how it is managed. Without a PAC code, your number stays with your current network; you would receive a brand new number from your new provider instead.
Do I need a PAC code if I don't want to keep my number?
No. If you are happy to start fresh with a new number, simply sign up with your chosen new network and they will assign you one automatically — no PAC code required. You only need a PAC code when you specifically want your existing mobile number to follow you to the new network. Many people are more attached to their number than they realise (especially if it is saved in contacts, used for two-factor authentication, or on business cards), so it is worth requesting one even if you are unsure.
What if I'm still in contract?
Your network is legally required to give you a PAC code regardless of whether you are within your minimum contract term. Requesting the code does not automatically cancel your contract or trigger any fees — it is simply a code.
However, if you use the PAC code to switch before your contract end date, you will typically owe an early termination charge (ETC) to your current network for the remaining months. Check your contract terms or log in to your network's online account to see your remaining balance. In some cases — particularly if you are only one or two months from the end of your term — it may be worth waiting and switching on the renewal date to avoid the fee entirely.
Ready to switch?
Compare SIM only deals before you request your PAC — prices update daily and the cheapest option shifts regularly.
Compare SIM only deals before you switch →Frequently asked questions
How long does switching take?
In most cases the entire process takes one to two working days. Texting PAC to 65075 delivers your code within minutes for most networks. Once you give the code to your new provider, they will arrange the transfer — your number typically ports over on the next working day, though some transfers complete within hours.
Will I lose signal during the switch?
There is usually a brief window of no service during the actual number transfer, typically between midnight and 6am on the transfer date. Most people do not notice this at all. You will receive an SMS from both your old and new network when the transfer is complete.
What if I don't receive my PAC code?
Your PAC code should arrive by text within one working day — Ofcom regulations require networks to provide it promptly. If you haven't received it after 24 hours, contact your current network's customer service directly. They cannot refuse to provide it. If they delay or obstruct, you can escalate to Ofcom.
Can I switch if my phone is locked to my current network?
You can still request a PAC code and switch SIM cards regardless of whether your phone is locked. However, a locked phone will only work with its original network's SIM. Ask your current network to unlock your phone (they must do this for free for most contract customers) or purchase an unlocked handset. Budget networks like giffgaff and Smarty supply unlocked SIMs that work in any unlocked handset.
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