Currently Being ModeratedDec 5, 2012 6:43 AM (in response to bzq)
If you've already replaced the sim & reset network settings, there's really not much left to try, except restoring your phone as a new device in iTunes. However, given the fact that you, your wife & another person all have the same issue, I doubt the problem rests with your phones. I'd go to AT&T & get yet another sim. If the problem still exists, go to an Apple store...have them run diagnostics.