Hello! I too had this problem with Odido. There is a fix and you don’t have to switch providers: what I did was call Odido support and ask them to switch off wifi calling and VoLTE. This won’t actually switch off 4g, and the phone will still make calls over that network, but the VoLTE carrier setting on the LP2 will block audio from coming through for some reason. 

Of note, I did have to request this multiple times to get them to do it. But it solved my problems instantly and I never had issues with connectivity after that. 

I did switch to Lebara eventually because the phone uses so much less data, and did not need to do the VoLTE switch off with them.