Life Source (blood donation). They are either calling to remind you of your upcoming appointment, or calling to ask you to schedule an appointment to donate blood. They will stop calling if you answer the call and ask them to stop calling (or if you make an appointment).
I get these calls from Life source almost everyday from five different numbers. they leave a prerecorded messege about blood donations. I have never donated blood! its really annoying. the calls started around august 2012 and they are more frequent now. I have had this same number for a few years.