It was a telemarketer phishing for personal information.  When I politely told him I wouldn't answer any questions until he told me how he got my number and how his service was related to me he hung up.  I never did find out what they were selling.  Probably selling the personal information they gathered by randomly dialing people.

Called..when I answered nothing but silence.

Nothing there when I answered except "Goodbye."

Nothing said when I answered

It was a telemarketer