I have a very strange problem and I am also not sure if it comes from my fairphone or my provider.
First about the provider. It is premiumsim from germany and belongs to Drillisch which belongs to 1&1 which rents into the mobile network of O2/Telefonica. Before my FP3+ I had a FP2. There I didn’t have the same issue but it was even worse. The network connection was really bad and it took sometimes more than 15 min to register into a network and get internet. Or I wasn’t reachable like my phone was in airplane mode…
But now it is like this. I receive a call or I call someone that doesn’t matter. Then I start talking and after 8 seconds or after 65 seconds or between the connection is lost. Also possible that the connection doesn’t lost. It is not reproducible! When the connection lost I got this very weird Message, first in german and then in english: “Die von Ihnen gewählte Nummer ist nicht vergeben”, " there is no connection for the number you have dialed"
My wife is using the same provider with the same contract without any problem but using a Xiaomi.
So any one else with maybe the same problem? Or must it be the provider? Or could it be that a deactivated google service/app is causing this?