Keeping an old number for a new phone

[hicks-75]

i have just upgraded my phone from an IPhone 11 to an IPhone 13 and want to keep my existing number used on my old phone for my new phone.

I have received the PAC code to do this a few days prior to setting up the new phone. I have now set up the new phone but my number has not fully transferred as I am still receiving messages to my old phone and not the new one. Is there anything I need to activate to make the transfer?

[Mark_Weinreb]

@hicks-75 I’m a little confused by your post. A PAC code is only used when switching to a new mobile network, not when upgrading your phone. If your old iPhone11 and your new iPhone 13 are both with O2, all you need to do is put your old SIM into your new phone. 
If, on the other hand, your phone upgrade involved changing networks as well, and you gave your (previous network’s) PAC code to O2, then you will need to be patient and wait until after the bank holiday.

I

[MI5 · Accepted solution]

@hicks-75 

To avail yourself of 5g you need to do a sim swap.

Tet from your old sim first Guide: Sim Swap: a mini guide 2017 update 

You will also need to sign out of your Apple ID on your old iPhone or iMessages will continue to be received by it.