I recently switched over to AT&T to get the iPhone 4s. I use to use an unlocked iPhone 3gs on iOS 4 with T-Mobile. When I was on T-Mobile I was able to send and receive MMS even without 3g or Wifi, (pictures, and text messages sent out to multiple recipients). Now, I can only send and receive them if and only if I turn on my 3g. It does not work when I am connected to Wifi. My friend has the same problem and she is using the iPhone 4. Is this an iOS 5 problem or and AT&T problem?