Scouts text the leader questions with yes/no answers to work out where they are.
Mobile phone per group, and one for the leader
Send a Leader out into your "playing area". They find a spot on a street somewhere and wait.
Scouts split into teams, each with a street map and a mobile. Scouts text questions (Are you north of the High Street?) to the Leader about where he is, Leader can only respond Yes or No.
Scouts keep texting questions (20 questions ish) until they find the Leader.
This could either be done live where they walk around the area or as a theoretical one where the Leader answers as if he was at the end location and the scouts just work off the map. If you do the theoretical version then you can do this on any map e.g. London, New York etc.
Another version could be to split Troop into pairs, one decides on their location, the other has to 'find' them by asking questions.... again only 'yes' or 'no' answers allowed.
EDIT : Have added in Communicator Activity Badge links, Scouts can be asked to use a variety of text language (some of which the adult leaders may even understand !!) and the speed of texting is readily assessed as the messages come through.
Have added Cub Communicator badge requirement