Originally Posted by
jonnyjetprop
I used to fly the route many years ago. The controlling agency had a call sign of "longrifle" and it was a marine controller. The AFM or some body may be able to dig up a frequency.
http://aeronav.faa.gov/pdfs/sw_59_18NOV2010.pdf
It looks like the freq is 123.2 I'd check to make sure that he has the authority to clear you into R2503
SOCAL or LA Center handle that now. I don't think civilian airplanes normally talk to Longrifle anymore.