Can't call on AT&T?

[mystery01]

When I make or receive a call with my Lumia 920, the other person can't hear me. The same issue is happening to another 920 on the same family plan. Other phones work fine. What is the problem? Is it an AT&T problem with this specific phone?

 

[Jazmac]

Clearly its the service. Call them and have them re-provision your phone. It could be you have a bad sim card too. That may need to be redone at the AT&T store.