Amtrak had the Qualcomm mobile data system system installed with keyboards in the cab and in the crew car. If you look at the top of the P42 from above you will see a white dome. Inside this dome is a rotating clam-shell that is constantly communicating with the Qualcomm transponders on several satellites. Amtrak can send text messages to the Engineer any place except in tunnels or stations where they are covered. Amtrak has predefined forms that either the Engineer or Conductor could fill out to report information or make an inquiry. The Conductor could inquire if what looked like available rooms were actually open to be sold. If the Conductor sold the room it was reported to the computer via this system so Reservations would not sell the room,
I just remembered that sold their Omni-traks system but there have not been an operational changes. As of 2011, Amtrak was still using this system installed in 1995, since it is mentioned in the 800 page manual.