2 calls at 2 am, no message, very annoying

Spineless bastard has called me twice around 2am and doesn't leave a message.
I have called back and a machine asks for a passcode. Spineless and I believe illegal.

Spineless b*****d has called me twice around 2am and doesn't leave a message. I have called back and a machine asks for a passcode. Spineless and I believe illegal.

I get this calls 5x a day from this number for the past 2 weeks. Every time I pick it, its someone different and I called back and it says to enter an authorization code. Is this some caller card number? Sounds like the authorization code message whenever I use a calling card.

I had a man (sounded like he was in his 30's) call me from this number recently. He addressed me by name, knew my profession and mentioned he had been referred to me by a friend. He knew my friends first and last name. This is seriously creepy...

Calls and hangs up. Tried to call back and it asks for authorization code. VERY irritating.