After transferring my physical GiffGaff, (O2), SIM from my old A22 to my new Brax3 I am no longer able to make normal phone calls.
Tracking this down I found that VoLTE does not work on GiffGaff. As 3G has recently been switched off in the UK and VoLTE functionality I understand this is now a basic requirement for voice calls.
Does anyone know how I can make calls on GiffGaff?
I faced similar issue with a different Telco- somehow started working after restarting the phone. The other possibility (guess really), is that a new sim for the same number may have 4G connection capability