Since I upgraded to Android 15 I can no longer make or receive calls.
Hello and welcome to the community
It would be helpful if you share more information.
For example: where you are based, what network you are using - which operator, 5G, 4G?
Has your operator recently switched off any parts of the system?
are you using one or two sims? how old are they?
what are the SIM settings? Have they been modified after the update?