I've had the s7 for about a month now, and get dropped calls on just about every extended call - typically about 30 minutes into the call. Many times, I'm sitting in the same spot, in my same apartment, without moving for the entire duration of the call, so in my case the dropped calls aren't due to moving from LTE-capable to non-LTE-capable areas. I've also had static/interference on just about every call, and folks on the other side of the line often get interference or worse, suddenly can't hear me at all even when I can still hear them.
I've tried the phone in a number of other places, both indoors and outdoors, and the call quality continues to be spotty and largely poor. Interestingly, I can usually hear the other person better than they can hear me, and while many times the other person has completely stopped hearing me mid-call, that hasn't happened in the other direction.
The phone is largely as it was from the factory/store - I've only installed a few basic applications (along the lines of Spotify, Speedtest, etc.), and have only tweaked a few basic settings.In any event, these call problems existed right out of the gate, before installing any apps. I've tried a factory reset - no help. The phone is running on 6.0.1 and has the Feb 2016 security patch.
I'm on Verizon, and never had this problem in the past, with my many other phones (iphones, Blackberries, and one Android), making calls in the exact same spot in my apartment at the same times of day/days of week. I didn't even know today's phones and networks were capable of such poor performance. (The earpiece volume is also nearly unusably low, but that's for another thread..)
I did find that the call quality was slightly better after turning off advanced calling, and switching from global networks to LTE/CDMA. But I don't have enough data points yet to determine whether this has helped with the dropped calls. I haven't tried wireless calling yet.
I do love the phone in most other ways - so have hung onto the phone hoping these issues are software-fixable. Still hoping for a solution!