Glossary

A computerized device used in taxicabs, courier vehicles, service trucks, and emergency vehicles to communicate with a central dispatch office. Mobile data terminals feature a screen on which to view information and a keyboard or keypad for entering information, and may be connected to various peripheral devices. Standard peripherals include two-way radios and taximeters, both of which predate computer assisted dispatching.

National Emergency Number Association

The North American Numbering Plan (NANP) is a system for three-digit area codes that direct telephone calls to particular regions on a public switched telephone network (PSTN), where they are further routed by the local network. It is applied to the United States and its territories; Canada; Bermuda; and many Caribbean nations.

In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path.

PSAP is an acronym/initialism for Public Safety Answering Point, an agency in the United States, typically county controlled, responsible for answering 9-1-1 calls for emergency assistance from police, fire, and ambulance services.

In communications and information processing, a receiver is the recipient (observer) of a message (information), which is sent from a source (object). Receivers decode messages

In trigonometry and elementary geometry, triangulation is the process of finding a distance to a point by calculating the length of one side of a triangle, given measurements of angles and sides of the triangle formed by that point and two other reference points.

Trilateration is a method of determining the relative position of objects using the geometry of triangles in a similar fashion as triangulation. Unlike triangulation, which uses angle measurements (together with at least one known distance) to calculate the subject's location, trilateration uses the known locations of two or more reference points, and the measured distance between the subject and each reference point. To accurately and uniquely determine the relative location of a point on a 2D plane using trilateration alone, generally at least 3 reference points are needed.

IP Telephony, also called 'Internet telephony', is the technology that makes it possible to have a voice conversation over the Internet or a dedicated Internet Protocol (IP) network instead of dedicated voice transmission lines. This allows the elimination of circuit switching and the associated waste of bandwidth. Instead, packet switching is used, where IP packets with voice data are sent over the network only when data needs to be sent, i.e., when a caller is talking.