Caller ID displayed as "ATT" following by an unrecognizable number. I let it go to my answering machine to screen the call. They didn't leave a message. I dialed back the number and for several minutes, the line continuously rang. Then I encountered a busy signal and I hung up.

I highly doubt that this is a legitimate AT&T number since no live person answered the line. Furthermore, according to whitepages.com, the number is classified as a "landline" but there is no name on file for this number.