Searched, didnt find anything... mostly a jumbled mess of threads... Brand new iPhone 5, updated iOS, AT&T, running LTE in a major 4G/LTE coverage market. When I make or receive a call, then disconnect regardless if I hang up or the other party hangs up first. My signal strength will drop to one bar for a few seconds, then display "NO SERVICE", then my signal will come back to full strength. This whole process takes place over 15 to 30 seconds. In my area I've always had nearly full signal strength where I live, work and play. Don't have any issues when surfing the net via LTE, just when I make or receive calls... Anyone have any ideas?