Ben Burtt discovered the "Wilhelm Scream" in some audio collection somewhere and brought it to the public limelight. Since then it's been used in A LOT of movies, with Ben Burtt deserving credit for finding it. It's fun to hear it, knowing it's an homage to Ben Burtt.
He even tried to make the Wilhelm Scream with his own voice in RotJ when Han knocks him into a pit in the Endor shield generator. :P
Can't say I know the "326-3827" reference though.
"Sir,we are beginning our search for these rumored 'underwater villages'.They will not stay hidden for long". -Battle Droid Commander OOM-9!