Get calls from this number frequently, but would never answer a call with "000" as an exchange {once had one on caller ID: 000-000-0000}. Called the number back once only moments after receiving call  only to get a recording telling me "it's not during their normal business hours". No ID of who it is or a means to leave a message...

person who called said his name was david and he was with at&t. wanted to upgraded my long distance service which i do not have with at&t. when told that he hung up.

Lady called to discuss AT&T business account.  Would not leave call back number.

when i called the number back it says the number has been changed or is disconnected. hmmmmm.