zTrip sounds identical to an app I envisioned in 2010 I called "Yo Taxi!" It would take your phone-reported GPS location and send it out to one of the affiliated taxi services (depending on who serves that location, cost, etc.) who would dispatch a cab to that point.
I'm kind of glad "Yo Taxi!" exists in some form now, what with the wheels (figuratively) falling off Uber and Lyft.
I'm kind of glad "Yo Taxi!" exists in some form now, what with the wheels (figuratively) falling off Uber and Lyft.