AT&T has just issued a statement on Twitter to its wireless customers to restart their phones if they’re having issues making calls. It appears many customers are having a hard time making phone calls and all AT&T can say at this point is to restart your phones, multiple times if necessary to reconnect properly to the wireless network. Some users have reported turning on airplane mode for a few minutes and then turning it off worked for them, so if restarting doesn’t work for you, give it a try.
AT&T is still investigating the root issue and we will keep you updated if we hear anything more.