How does Birdwell know to tell the Brooklyn guys to find Milgrim at the Korean Laundry?

Is it simply via the cell call to Fish? Does Birdwell call that number and ask the girl on the other end: "Is there some jive-ass white motherfucker in your life who used your phone?"

Do the Brooklyn boys put the word out on the street to be on the lookout for a droopy eyed addict type in a stolen Paul Stewart overcoat?

How do you think "The Moors" find Milgrim?

How come you gotz to be startin' with the interesting questions when my copy be loaned out, yo?

Nevermind, Gibson explains it later in Houdini. Birdwell socially engineered the girl who left the phone.