Who called from 2137108121

CALLED TWICE AT 3:00 AM. THIS MORNING.JAN 22,2010. a CALIFORNIA AREA CODE.

I got this call for two nights so far around 12-1am.... Im a college student I do not need some kind of service or w/e calling me in the middle of the night!!

At 5:38 A.M. local time I received a one ring hangup from this number.

at 12;15 A.M. ONE RING AND NO ONE AT THE END OF THE LINE.....

I got the same thing, one ring then a hangup... anyone know what this is?.. why they are doing this mess?