What phone do you have?
What plan are you on?
Choice 3.0 Cell + Data
Does your plan include data, or just talk & text?
See above - yes
I’ve been having this issue forever. About 10 minutes into a call, the volume suddenly drops significantly, becoming very quiet no matter how much I turn up the volume. If I end the call and call back, or have the other person call me back, the volume is restored for another 10 minutes or so.
I have not tried anything to fix it, and I only notice it sometimes since most of my calls are not long enough to trigger the effect. If I wait long enough, sometimes it will fix itself.