I replaced 3 iphone 3g's with 3 new iphone 4's on my family plan. 2 of them are working just fine. The other one is unable to send or receive texts or mms. Anyone else having this problem? Or anyone that can suggest how to fix this? I wonder if I might have misstyped in the ime or SSID info on the at&t page incorrectly on that one unit. This is a non jail broken phone. Just a regular 3g.