Quote Originally Posted by dclamp View Post
It is referred to as the ANI/ALI system. Automated Name Information and Automated Location information. For Wireless 911 calls it depends on the age of the phone. There are two different phases. Phase 1 calls will give you a very vague location based only off of the currently connected cell tower. Phase 2 will give you GPS coordinated along with a percentage of how accurate it is.

Sometimes I will give a w911 call that will show a giant circle around the entire city, Phase 1. Other times it will show me exactly what room in a building they are calling from.

As for landlines, there is something calls a MSAG - Master Street Address Guide which has an address for every single phone number in a city. As well as who is the Police, Fire and Ambulance jurisdiction to respond so that all calls get routed to the nearest PSAP.
Are you a 911 operator?