this number showed up on my cell from MRC. I called them back and said I was put down as a contact for someone they were trying to contact (my sister). They would not identify the nature of the call, so why would I give them my sister's number? Called again the next day so I called back and got the rudest representative who was put out at how upset I was. Excuse me, who's calling whom here? So anyway, this place takes your number off the "list" but you have to be blunt and say that verbatim.
hi, i was getting multiple calls (4, 5 a day) from this number but they would never leave a message. i finally called back and yes it is a collection agency. i just asked who they were trying to reach, and turns out they had an old number for someone else and ended up being my cell number. they were nice, i told them that person no longer had the number. we'll see if they call back.
update: answered the phone and it was a collection agency looking for someone else with the same name... possibly just calling from a list of matching names composed from nation wide telephone directories