No Caller ID/No message

Caller did not identify themselves and ask for two people we do not know.  They ask for Randy Johnson and Donna Sampson.  There has been more than one call after telling them they have the wrong number and we do not know these people.

i got a call from this number also its was a collection agency for unpaid student loans...only problem....i never has one...

Leaving a message on my answer maching by asking me by just my first name (as if they know me) to return their call without letting me know who they are and what they want?