Update: Attempted calling ATT, and was NOT helpful at all, nothing came of it.
As of 2:30 PM local time I gradually started receiving msgs again from non ATT carriers.
Bottom line, just like termleech said, it fixed itself after more than 13 hours down. I guess this was just some random event. I had never had this problem before. I guess I better be prepared for the SMS approach not to be as reliable anymore.
Thanks for your posts!
Let this thread remain in the archives in case someone else has a similar issue