Answered "Hello" to the dead air of a robocall. A man came on the line after several seconds and said "Hello?" After I responded, "I already said hello once", he hung up without another word.

No one answered after I said 'hello?'. I called back and rec'd automated recording (something to the effect of) 'The person you're calling has voicemail that has not been set up yet. Good-bye." And, automatically disconnected.

No message.

Stop phone soliciting

This number called twice within an hour.  We did not answer.  CallerID said only "wireless caller".