I also received two of these same voice mails and the message contains the same sounds as reported by others about cellphones in pockets, etc. There were actually two separate messages left, one at 7:59pm and the other ar 9:34pm, but it was the same exact message of just background noise. That being the case, this doesn't appear to be a pocket dial accident, but someone is sending this same message to others.
They got me this morning. I sort of had fun trying to figure out where they were. My guess is a Starbucks. They must get off on random calls to people, leave the phone on and let the called number enjoy their life. This is probably the high point of this guy's day.
called our business phone 2 times in a row, voice mail message was "if you wish to have your number removed from our list, press 1, then very loud white noise until voice mail cut them off.