Startup Idea : Taxi nearby

We face big difficulties in relation to taxi. In my country taxi works like this: The customer call and ask for a taxi to a taxi company. Once this is done the company asks the customer location and if the customer explain well, the customer will get the taxi on the spot with somes delays depending on taxi distance. Now let me explain the big deal of it. 1. There are times that the client does not know its location. 2. Waste of time trying to explain the location. 3. When this finally explain the location, the taxi company searches for the nearest taxi to you (this also takes time) and if has no taxi available, the customer must call another company and do it all again. What I want to do is develop a taxi network system that will work as follows: 1. Client-side software containing all possible taxi of the current region within a certain radius. 2. Companies-side Software web-based that controls all taxi company and receives customer orders and demand for the nearest taxi on your location (by GPS). 3. A taxi-side device that receives the client's location (also by GPS) and provides the shortest route automatically. 4. Server that controls all taxi and their respective companies.