Problems with TXT messaging

I thought this had been addressed before, but I searched the forums and didn't see any threads pertaining to my question/problem.

My problem is: I don't seem to be getting txt msgs from people on other carriers and vice versa. Do I need to go to an AT&T store and talk to a rep about getting this fixed, is there a fix for this or is this a bug and I need to wait for the next s/w update?