I used the Cel Cab Taxi service in India recently and I must admit I was impressed. Here is how it works. You call up a number and tell them when you want a cab and where you need to go. They get your address and phone number. It is as simple as that.
A few minutes (say about 20 minutes) before the arrival of the taxi you receive an SMS giving you the Taxi’s ETA (estimated time of arrival). The Taxi turns up and drives you to your destination. An hour or two later your receive an SMS seeking your feedback on the service!