The purpose of this document is to define procedures for testing the interoperability of subscribers/repeaters between different manufacturers, different models of the same manufacturer, and different firmware upgrades of the same model. This is the first of a series of documents, all of which discuss procedures for interoperability testing of TIA102 digital radio equipment. The contents of this document are confined to conventional voice systems. As currently envisioned, other documents in the series will address capabilities of over-the-air rekeying (OTAR), trunking, data transmissions, and networking. A prerequisite for interoperability testing is the requirement that the unit under test (UUT) meet the conditions of conformance and performance as designated in the TIA102 standards.The reader is referred to document APC025.940811.2.3 (Lockdown Overview) [6] for a discussion of the General Systems Model and various interfaces.