Who called from 7206397859

Caller ID identified call as Denver CO. I don't know anyone or do business in any part of Colorado so I didn't pick up. However, a message was left on a second call from the number the next day. The phone message was nothing more than a bunch of strange noises....don't know if this is some kind of prank or what....

This is fax spam. The noise you heard is the sound of a fax machine trying to connect.