My Moto G4 Plus started having call quality problems about 3 months ago. The call connection sounds like a very poor quality VOIP phone with distorted voice and missing words during the call. Sometimes it is almost impossible to have a conversation because it is doing this every couple seconds, other times it is more like every 10 seconds. For all other uses the phone seems to work just as before the problem started.
I have a Moto G4 Plus running Android 7.
My Plan is: My Choice + 1 GB