Called my cell, did not leave a message

Called my cell and knew my name. Asked for a friend of mine by first and last name.  She said her name was Krystal and that my friend put me down as a reference but didn't ask me any type of reference questions, nor did she state what company she works for.  She asked for my friend's phone number but I refused to give her any personal info about him and I could tell that she was irritated by that and asked if I could give my friend the number that she called from.  I'm guessing that the call might have something to do with collections but I don't know how they got my number.

Called my work # but did not leave a message.

Did not answer

Called my work and didn't leave a message. After reading these posts I will make sure to not pick up.

Thank you all for posting