Same complaint as others, several calls a day, no voicemails left and if I call back to the number I get the vm that the extension is unavailable. I don't use my home line much and so I hadn't noticed it until the phone rang when I was actually home and I saw all the missed calls. I just filed a complaint on the do not call reg site. Some of the calls the caller ID says "unknown" and some it says "preferred guest."
I to am getting these annoying calls. I called my phone company and they suggested dialing *77. This puts a block on all "unavailable" numbers, but will let the caller, if valid to follow instructions in order to connect the call. This SHOULD take care of your problem. I recommend you call your own phone company and see if they support the *77 block.