unknown caller

i've been receiving these calls weekly for several weeks now.  i usually don't answer calls from numbers i don't recognize or expect, believing that MOST people will leave a message.  this number NEVER does.  what is going on?

called me twice- don't know them

I've also gotten two phone calls from that person and I don't ever answer unknown number.. I thought that maybe they would leave a message but the never do. Has anyone talked to the person? I seen someone said something about a collage student some where.. I'd like to find out who it is.