How to disconnect your old non-O2 number

Are you switching to O2 and no longer want to keep your old phone number? No worries, your new O2 SIM will come with a new phone number for you to claim when you’re all set up.

You’ll need to disconnect your old number to avoid being charged by your old provider. You can do this in My O2, and find all the information you need to help you along the way.

To disconnect an old number, you'll need to ask for a Service Termination Authorisation Code (STAC). It's quick, easy and free to do this – simply text 'STAC' to 75075 from the number you want to cancel. It should arrive within 60 seconds.

Alternatively, you can contact your own network provider for your STAC.

Once you have your STAC, give us your code in My O2 and we'll then use it to work with your old network to cancel your number.

If you’re switching to or from Pay As You Go or Pay Monthly, you can choose to get a new O2 number with your new SIM and you won’t need to ask for a STAC to shut down your old one. You can find out what your options are for your old number by contacting us when you make the switch.

_{Last updated: 02/02/2026}