this morning I had this situation on my new FP3+ with OSv77, while doing a VoLTE-call in the network of Vodafone Germany:
I called somebody, talking for 10 seconds, then the call disconnected and the dialer showed the text in German “Server nicht erreichbar” (Server not available).
I called again, same message and disconnect after 10 seconds.
Then the other person called me, same message and disconnect after 10 seconds.
Then I rebooted the phone and calls are working again. As the problem disappeared after rebooting, I guess the network can not be blamed for that, but the phone instead.
Anybody else had this problem? Any ideas how to make sure this will not happen again?
Thanks for help and informations!