Untitled

I have a table "cdr" with 3 fields.  

in_trunk
out_trunk
session_id

each row has one of the trunk fields populated and the other null.  I need to select a result set that will have all 3 populated values.

exe: trunkX, trunkQ, 112fadav121ac129a8hv


I have tried subqueries and joins and all sorts of crap and im just not getting it.. some times.. i litereally hit a wall with this stuff and i just need some one to point out what i just am getting.