New iphone 12 mini cannot make or accept phone calls

[PWX]

Has anyone else had this problem? Would welcome helpful suggestions. O2 appear to be closed to customers needing help until next Monday. I suspect it's something simple to many people - unfortunately not to me. Is there a series of steps needed to disable the phone number from being used by an old sim and phone - which will allow a new phone and sim to begin operating? Thank you in advance...

[jonsie · Accepted solution]

You need to do a sim swap from your old phone sim

Follow this guide

Guide: Sim Swap: a mini guide 2017 update