Switch from O2 to Three
Keep your phone number when you switch from O2 to Three. Here's how in 3 simple steps.
Switching from O2 to Three takes you from the Telefónica network to Three's independently operated infrastructure, which is known for competitive unlimited data plans and growing 5G rollout. Three also offers inclusive roaming in many destinations at no extra cost. The entire switching process can be completed in minutes, with your number porting over within one working day.
Important Warning
Do NOT cancel your contract manually. If you cancel before transferring your number, you will lose it permanently. Your old contract will automatically cancel once the transfer completes.
Pre-Switch Checklist
- Back up your data: Contacts, voicemails, and saved messages won't transfer.
- Unlock your phone: Ensure it's not locked to your old network if you plan to keep using it.
- Check Early Termination Fees: Text INFO to 85075 to see if you'll incur charges for leaving early.
How to Switch from O2 to Three
Get your PAC code from O2
Text PAC to 65075 from your O2 handset to receive your PAC code by return SMS within one minute. You can also obtain it by calling O2 on 202 from your O2 phone (or 0344 809 0202 from another phone), or through your online account at accounts.o2.co.uk. The PAC code remains valid for 30 days from the date of issue.
Give your PAC to Three
Choose your new Three plan at three.co.uk, in a Three retail store, or by calling 0333 338 1001. When signing up, select the option to keep your current number and provide the PAC code from O2. Three will initiate the number port as soon as your new SIM or eSIM is activated.
Wait 1 working day
Your O2 number will transfer to Three within 1 working day. In most cases, the switch happens within a few hours. You will get a text message on your new Three SIM confirming the transfer is complete. At that point, your O2 contract is automatically closed.
Transfer Cut-off Times: Submitting your PAC code before 5:30 PM usually means your number will transfer the next working day. Submitting it after 5:30 PM or on weekends/bank holidays will add an extra working day to the process.
Final Bill: You'll receive a final bill from O2 shortly after the transfer is complete. This covers your usage up to the date of the switch.
Things to Check Before Switching
Verify whether you have any remaining months on your O2 contract, as early exit fees may apply. Ensure your handset is unlocked for use on Three — O2 devices bought after December 2021 come unlocked by default. Download any content or data tied to O2 services before the switch, as you will lose access to O2 Cloud and O2 Extras.
Different Network Coverage
O2 and Three use completely different network masts and frequencies, so coverage can vary significantly between the two. Three has strong 5G coverage in major cities but may have weaker indoor reception in some rural areas. Check Three's online coverage checker at three.co.uk/coverage to make sure you will get a good signal where you need it most.
Ready to Switch to Three?
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