http://www.youtube.com/watch?v=dcc3wdKZ-as Watch the video. Basically the phone acts fine, suddenly the cell network goes to one bar, wifi shuts off, then I get "No Service". Then 5-10 seconds later it reconnects everything. It behaves like this for 5 minutes, then it acts fine again. 20 minutes later, it happens again. I tolerated it for 4 months until this nonsense cut off my call. I don't know why it does this. iPhone 3GS pre-2009 GSM Model (Jailbroken) ultrasn0w installed (unlocked my phone) iOS 6.1.3 Modem Firmware - 06.15.00 EDIT: Forgot to mention, this never happened until I jailbroke my phone and used ultrasn0w.