Omar approaches from the front carrying a shotgun while nonchalantly whistling "The Farmer in the Dell" which scares the dealers, who then run into the alley where Brandon and Bailey, also armed, are waiting.
The pager messages were encoded to prevent easy tracing of the telephones used, all of which were public telephones.
Officer Ellis Carver tells Bodie Broadus in season one, episode five ('the pager'), that he was brought up on the Flag House Courts project.