It's someone using a predictive dialer (this is when a computer calls several numbers at the same time, and then hangs up on all the other calls but the one that answers first, or specifically is waiting to leave a message or not). Irritating, and they've toyed with the caller ID to give this impossible number. You can call the FCC etc. and report it if you want.
WARNING--BEWARE!! These callers are B I G credit card criminals, known as the card service scammers! Under NO circumstances, give these lowlifes your credit card number, or you will regret it forever!
Female caller asking to speak with whoever's in charge of the AT&T account. I played dumb and wasted her time, asking what it was about even though I knew it was likely a scam call. Finally she got frustrated and said she'd call back later.
SCAM , they are not calling from ATT . This is how it works , low introductory rate to lock you in then your credit card will be charged with amount higher than promised. These days , no one should accept anything form anyone who calls you