I got a couple of calls from 781-751-4203, too.
It is the pheresis department of the American Red Cross scheduling folks in Massachusetts.  Lynn, MA is a possibility.
I am a platelet pheresis donor.  Hadn't seen that number previously.
I believe these folks "just" call people who already donate.  Blood platelets are given to deathly ill patients, A.I.D.s and Cancer patients especially.
Once you're scheduled it is very important you don't skip it. There are times where someone is waiting for it with a dead immune system. They die without it.
FYI:
I heard on the news that the Red Cross is very low in whole blood. (As of Feb., 2014).

Didn't pick up, but didn't leave a message, second time this person has called.