how do I keep my old number on a new sim?

[newsue]

I have just opened a new account with O2. They said I could keep my old number, but when the new sim turned up it has a new number on it. How do I change it to my old number?

[madasaf1sh]

@newsue

Where you bringing a number from another network? As if so you will need to obtain a PAC code from your old network.

Full details here: https://www.o2.co.uk/help/device-and-sim-support/how-to-keep-your-mobile-number