Taxi booking and dispatch system

Taxi booking and dispatch system with manual and auto dispatch of jobs to PDA devices which will be connected to GPS (Exists) with all signalling via the GPRS network. Fallback to GSM in the event of GPRS dropout. Smart allocation of jobs to best Taxi using GPS location and driver status.. closest driver or closest driver waiting longest. Nice to have credit card payment and accounts for customers and drivers. More info as required. PDA client required but info and code exists for guidance or modification. Mike