3 to 4 times a day.
This is vile, putrid, and detestable.
First off there is no "they". "They" do not hang up on you, it is a machine.
This "corporation" is some guy with a phone dialer in his basement.
The only thing you can do is to report it EVERY time to your phone company, at least when they do catch him they will have a long lost of complaints.

On numerous occasions, we have recieved phone calls from this number. Whoever is on the other end holds the phone, then hangs up. When we call it back, but all we get is a busy signal. Sometimes the number shows up and other times it shows up as unavailable. Anything that anyone can tell us to eliminate this problem would be greatly appreciated. Thanks.

Call three times and hung up.

They've called me (in MA) at least three times in the last week. Free airline tickets which I "won"...the message changes slightly each day. Today the caller "Josh" said this is the last day he can hold them for me...I hope this means they'll stop calling...

It would seem this is some type of scam.

Calls coming into fax line and regular home line at all hours - pick up and it goes to a busy signal. We lived in Seattle so we think it's a friend or something, esp. at 11 p.m. Called the # back and it goes to a busy signal.