They call so you will either answer it or call them back and then they will know a "real" person lives at your number and you will be getting a lot more calls like this except now they may be scam calls saying you owe money or will be arrested for fraudulent checks or something crazy.
Best not to answer calls that you do not who they are from or at least let the answering machine pick it up. If it is something legit they will leave a message otherwise half the time they won't.
Notice most of our posts on this number are pretty recent? It must be the "new" phone number they are using to call and start their scam.
I have been getting these types of calls for the past 5 years and nothing has come of them.
I don't pick up and I don't call back.
I called a friend with a different number than this. When I hung up, my phone screen said "do you want to add this number to your call list?" It was not her number so I saved it as her "work" number. I then stupidly called it back to ask her what the deal was with the different number and got the recorded message people mention above. I did a reverse search and found out its location is either in the Florida Keys or offshore of the keys.