APCO Project 25 digital radio systems will optionally support a trunking mode of operation. This document provides details of the procedures required such that@ where systems are configured in the trunking mode@ voice and data services will operate in accordance with the goals of APCO Project 25: a. support any Project 25 trunking radio; b. interoperate across any Project 25 digital radio trunking system; c. independent of the particular Project 25 equipment manufacturer. This document describes the procedures necessary to support the APCO Project 25 Trunking services@ and provides the necessary guidelines for infrastructure requirements to support interoperability of these trunking services. This document is consistent with other pertinent APCO Project 25 documents@ namely: a. Project 25 Common Air Interface; b. Project 25 System Model; c. Project 25 Trunking Control Channel Formats; and d. Project 25 Trunking Control Channel Messages. This document does not explicitly address any procedures required in support of any non-trunking (e.g.@ conventional) modes of operation.