Every time I remove my phone from my pocket to use it, It shows up as "NO SERVICE" and then after giving it about 10secs it shows my service provider "ATT". it happened quite a lot in the last 3to4 days. It also shows no network when i keep my phone aside and don't use it for a while. Not sure if its the phone or the network. I have owned 4S and this didn't happened on that phone so I am pretty sure its not the ATT network. Is anyone having the same issue?