there's a new scam going around. they call people and hang up after the first ring. they want you to call back so they can somehow start charging all kinds of calls to your number. i don't know exactly how it works but they did a news report and i also read an article on this. BBB is warning people not to return the one ring hang up calls.

Ditto.

Same story.  'Wrong number', and call disconnects.

Called today, man said "hello" before I greeted him. When I did, he said, "Oh sorry I have the wrong number".  Hung up.

Same here.  Hello, hello. . .Oh sorry, wrong number and hangs up.  I reported it to the FCC.  I receive these types of calls numerous times through the day, at work.  It's so frustrating to ask a client if they would hold for a moment, so you can answer another call, only to have it be a prerecorded message.  And, it doesn't give you an option to be removed from their list!!!  

Here is a link to file a complaint.  http://www.fcc.gov/complaints