Head to the left and exit the room, keep heading left past the gate.
Check the graffiti out and open the phone box, you need a dime
to make a call, make a note of the name
(I think it's random).
Switch to Reyes and head to the bank, you should see a dime
on the floor. Pick it up and head to the Quickie Pal and drop the dime
into the Sewer manhole cover.
After the short cut scene (still as Reyes) head on over to the phone box on B street. Look at the phone book and then look up the name
from earlier. Make a note of the phone number
Switch back to Ray and head back to where you woke up and go through the north exit. Grab the dime
on the floor and head back to the phone box and graffiti.
Use the dime
and dial the phone number
, speak to some random guy. Grab the dime
from the coin slot and exit right (back to the gate).
The Sheriff-a-reno should open the gate and set you free.