Hi - it would appear that my son’s phone isn’t switching between networks. He can’t call or text some people. He has a new iPhone 12. My husband and I gave the same phone and don’t have the same problem. It seems it’s looking for 5G and when it can’t find it, the phone isn’t working. He can call and text but it’s coming from **Personal info**
Turn off 5g in the network settings.
Also check Settings >Phone >My Number for the correct entry and edit it if not.
You need to use your old sim or do a sim swap if you want to use the new sim Guide: Sim Swap: a mini guide 2017 update
I don’t think I should need to as I used o2 refresh and have received messages to the new phone saying the refresh has gone through. And the old phone has no network either. The assistant in the shop said it might take 24h for the swap to happen (indicating to me that it was automatic as I’ve agreed to the t&cs and upgraded) but this hasn’t happened.