You send your location to let Sarah Briggs know that you need your Titan near your location

Sarah Briggs: Talking to you in your radio helmet Stand by for Titanfall

Legion: Drops down from mother ship then land on the ground while female robotic voice Legion, ready for action my Pilot stand up

Legion: Grab her Predator Cannon from her back while female robotic voice Ready to follow your lead my Pilot

Legion: In guard mode while scanning the area