Shows up as "ADSL NO LOCAL" - leaves no message (of course)

Number listed, unknown name - I lift the receiver, wait for the relay click-in, then hang up.  Doesn't stop them, but at least the call doesn't go to the machine so they can't tell if they've reached a valid number.

Got their call 10 minutes ago.
Did not answer.
Since I've got "caller display", I dialed back the number.
O surprise... This number is not in service. (Recording)

It's a safe bet to consider this number a scam attempt.

just got a call from this # from  some one speaking a different language telling me he could give me a better rate on my credit card. i asked him how he knew if i had a credit card and he said i had both visa and mc, knew my last name and the phone # also.  i asked where he got his info from and he said their researchers  get it, he works for visa, mc, and large banks. he left out that they always say  they record the conversation for what ever reason. def a scammer. when i hung up i called the # on the caller i.d. and it sounded like a fax machine.

Called at 19:10 EDT. No Voice, just relay click.