How to Switch
Switching Networks.
Keep Your Number.
One Working Day.
Switching UK mobile networks is free, straightforward, and takes just one working day. Here is the complete step-by-step process.
How to Switch
Switching UK mobile networks is free, straightforward, and takes just one working day. Here is the complete step-by-step process.
Under Ofcom regulations, you have an absolute legal right to keep your mobile number when switching to any other UK network. The process is called number porting and is completely free. Your current network cannot: charge you for a PAC code; delay providing it beyond 60 seconds from your request; make you speak to a retentions team before providing it; impose any condition on providing it; or prevent you from switching while you have remaining credit on a PAYG account. These are not optional — they are legal obligations all UK networks must comply with.
Text the word PAC to 65075 from the mobile number you want to transfer. Within 60 seconds you will receive a text reply containing your free PAC (Porting Authorisation Code) — a nine-character code consisting of three letters followed by six digits. The code is valid for 30 days from the moment it is issued. Keep this code safe: you will give it to your new network when you sign up to transfer your number. You will also receive an automatic message with the cost of any early termination fee if you are leaving before the end of your contract minimum term.
If you do not want to keep your number — for example, if you want to start fresh with a new number — text STAC to 75075 instead. This provides a Service Termination Authorisation Code that cancels your current contract without triggering a port.
Before signing up to a new network, check your current contract end date and any early termination fee. Leaving before your minimum term typically means paying the remaining monthly airtime charges (not the device cost on split contracts like O2 Refresh). For most contracts, the termination fee reduces each month as you get closer to contract end. Calculate whether the savings on your new plan outweigh the exit fee before proceeding. Networks' retention teams often offer competitive deals to keep you — calling your current network before switching is worth the 10-minute conversation. They may match or beat a competitor's price.
Since December 2021, Ofcom has required all handsets sold by UK networks to be supplied unlocked — working with any UK network's SIM card from day one. However, phones purchased before this date may still be network-locked, meaning only the selling network's SIM will work. To check: try inserting a different network's SIM card. If it works, your phone is already unlocked. If it asks for an unlock code or displays an error, contact your current network and request an unlock — this is always free and typically completed within 24–72 hours. Some older networks (especially on flagship phones) have specific unlock request forms in their apps or websites.
Choose your new plan and sign up online, in store, or by phone. When asked for your existing number, you will provide your PAC code (the nine characters from Step 1) alongside your current phone number. The new network manages the entire process from this point. Your new SIM (physical or eSIM) will arrive or be activated — typically within 24–48 hours for a physical SIM, or immediately for eSIM.
Once your new network has submitted your PAC code, the port is triggered. UK regulations require the transfer to complete within one working day. The switch typically happens in the early hours of a working day, with a brief service interruption of one to three hours during the transition window. During this period, calls and texts to your old number may not connect. After the transfer completes, your new SIM activates on your old number and your old contract is automatically cancelled. You do not need to contact your previous network — the port completion triggers the cancellation automatically.
Before signing: use the new network's coverage checker for your home postcode, workplace postcode, and regular commute route. Confirm whether EU or international roaming is included if you travel abroad. Read the annual price rise clause and confirm the exact pounds-and-pence amount (required to be disclosed upfront under Ofcom's January 2025 rules). Check whether 5G is free (it should be on all modern plans). Verify that WiFi Calling is supported on your specific phone model if you have poor indoor signal at home. And check the contract length and any early termination fee structure, so you know your exit cost if you ever need to leave early.