She finds a scrap of paper in her pocket, and leans on a nearby wall, writing her number on it, and handing it to you.
"Goes without saying, but don't send anything stupid, since NATCA means they'll read all our messages. They've got a lot of texts to read, though, so they won't notice that you suddenly started talking to a random stranger unless they're monitering you specifically. Send me something that seems like a perfectly normal message. If you want to meet up, mention the meeting spot vaguely, like the café near the place we met, rather than using any street names. If you need to warn me about anything, make it sound like it's about something mundane. If they find out where I live, ask me when I'm planning on moving, for example."