When a restart the phone everything is alright, but after a while when trying to call any number my calls get immediately dropped and it says Call ended. Happens both in owner and secondary profile, I have LTE or 5G mode set, didn't touch carrier settings. My carrier is Hungarian Telekom. Internet works fine.

In network settings, do you have VoLTE (4G Calling) enabled, and if so, have you checked whether it supported by your carrier on your Pixel 8a device?

Are you Roaming or are you directly connected to your network provider?

    treequell I have VoLTE enabled and it should be supported, although it's strange because devices display VoLTE usage on the notification bar, but my devices never do, despite me checking with the carrier that it is indeed working and the carrier config displaying VoLTE. I'm not roaming.