Introduction and Scope Project 25 digital radio systems will optionally support a standardized set of data communications services. This document provides a detailed specification of the circuit data communication services such that@ where these data services are enabled@ data connectivity will operate in accordance with the following goals: ? Through any Project 25 radio ? Across any Project 25 digital radio system ? Independent of the particular equipment manufacturer ? Adherence to the Common Air Interface ? Independent of trunking or conventional system modes