Taxi drivers must have a smartphone in order to use the application and to manage incoming calls.
A standard user is whoever needs a taxi service, using the new available technology. He must have a smartphone or a device with an internet access so he could use the web application or the application itself.
There is an administrator level, which is not specified, but can be useful for checking accesses and statistics.
Web application and app have the same functionalities.
Users have a GPS-enabled devices.
When a passenger requests a taxi, at least one is always available.
A shared taxi can be reserved at most for the number of passengers that the car can contain. (forse non qui! )Domain Property