Had it for 5 months no issue thus far, not even over heating. think I got a safe one.
I had this issue once apon a time when I used two sims, one for 3g dongle and one for phone. When I used the one sim, it would drop the connection of the other, and visa versa. Not quite the same, but feels similar.
Apparently with international networks, there is an option to make this work. Im curious to find out if any other S7 owners experience the same thing.
Had the same issue on vodacom where could only access data or voice never both. On my international sim could email while on a call. Ported out to Telkom and phone no longer dumbed down to vodascum levels.