A Computer Assisted Dispatch or CAD system is a highly specialized computer system that is designed to automate the flow of information through the emergency communications center. CAD systems take the initial call-for-service data, link it to pre-defined data required for the emergency response, and switch the call to the various operators in the center that are responsible for dispatching the emergency response.
For example, when an emergency 911 call comes into the center, the CAD system links to the phone system and displays the caller information for the answering operator. The location is automatically checked by the system to see if there are contacts, alerts, warnings, or other data relative to the location. It also checks the previous call history at the location. The system then allows the operator to enter other data about the nature of the call, such as the type of emergency, details about the emergency, etc. The system then creates one or more calls and forwards the information instantly to the radio operators that will send the emergency response. The systems have a series of commands that allow the call to be tracked during the complete emergency process. They also provide a series of safety timers that help insure that calls don't get ignored and that responders to the emergency are safe. 
An important side benefit of CAD systems is that they provide complete statistics on response times and load levels both in the communications center and in emergency response agencies. This helps provide management with the information necessary to determine the staffing levels required to meet the communities emergency response needs.