Sentence:  “They have a little network of women that watch out for each other,” Morford said. That means that if one prostitute doesn't come back after going out on a <WSD>call</WSD> — whether it's an Internet prostitute or a streetwalker — and the other women can't get hold of her, they get scared, close up shop and won't work, Morford said. 
Meaning of the word marked with <WSD> tags:  A meeting with a client for paid sex; hookup; job.