INTRODUCTION This document has been developed with input from the APCO Project 25 Interface Committee (APIC) Compliance Assessment Process and Procedures Task Group (CAPPTG). The impetus behind the development of this document is the need for standardized@ functional interoperability testing of conventional subscriber units and Fixed Network Equipment designed to the complementing documents that comprise this suite of standards. The purpose of this document is to define functional procedures for testing the interoperability of subscriber units@ and Fixed Network Equipment in conventional voice operation and supplemental data operation between different manufacturers@ different or same models of the same manufacturer@ and different firmware versions of the same model.