Now, Lelouch stole one of the terrorist's communicators, originally intending to turn it over to the authorities, but now he uses it to rendezvous with the resistance.
There's no news of what's happening in the ghetto, which means they want to keep it quiet.
This means they can't call for reinforcements. Lelouch helps pick off Britannian Knightmares, and rescues Kallen. Conveniently, there's a train full of spare Knightmares. Lelouch makes an offer to the resistance: do what I say, and you can win.