don't know who this is

Keep calling everyday and asking the information about the company. After being asked do not call anymore they keep calling.

I received a call rom this number and when I answered it there was no one there...or at least they weren't saying anything so I hung up.

I tried calling back but I received a pre-recorded message saying that this was not a working number?!?

I thnk that it could very well be a pay phone!