Good taxi service and data gathering

I had to drop my car off at the garage for a service this morning and rang for a taxi to take me to the office. It was interesting to note that they seem to store the last address that you were picked up from associated with the telephone number that you rang from.

I have noted this before, but mistakenly thought -as I'd only rang for a taxi from my home address- that they had my home address linked to my land-line number. In any case the service is excellent.

I was wondering what system they use for this, and was wondering what additional information they hold on customers and for how long? If any you readers are taxi-drivers and use a similar type system, maybe you would be kind enough to share with me?