Most of the time, the call fails with "Anruf fehlgeschlagen".
Sometimes, for no obvious reason it works on the volla phone. I found no way to reproduce it.
Sometimes, for no obvious reason it works on the pixel 3a for 3-6 seconds. Then the call is canceled. I found no way to reproduce it.
Switching the sim card to another provider works at least at the vollaphone. Not tested for pixel 3a.
Steps to reproduce
Insert a spusu sim card, make a phone call.
Expected behavior
A successful phone call should happen.
Actual behavior
Most of the time, the call fails with "Anruf fehlgeschlagen". Sometimes, for no obvious reason it works on the volla phone. I found no way to reproduce it. Sometimes, for no obvious reason it works on the pixel 3a for 3-6 seconds. Then the call is canceled. I found no way to reproduce it.
Switching the sim card to another provider works at least at the vollaphone. Not tested for pixel 3a.
Logfiles and additional information
This for a failed phone call on vollaphone: https://pastebin.com/WdF6gw4e