You're in the street and feel a sudden urge to play football? Just walk over to the nearest of the CALL A BALL kiosk, a kind of ball dispenser. You then send an SMS detailing the kiosk's number to CALL A BALLs communication center, which then sends a message authorizing the dispensing of a ball. Thanks to the RFID chip embedded in the ball, the center knows at all times where the ball is.
If you want to find people with whom to play ball, all you have to do is register as a 'baseplayer' at one or more kiosks. Then send out an SMS containing the codeword 'Challenge' to the kiosks of your choice, which will then relay it to your teammates and opponents.