Project 25 Purpose

The Project 25 standard enables interoperability among multiple manufacturers’ P25 products designed to the P25 standard. The P25 Common Air Interface (CAI) is the most widely deployed P25 interface enabling interoperability between P25 radios and between P25 radios and P25 infrastructure regardless of manufacturer. Public safety users can now obtain documented proof of interoperability between P25 Phase 1 CAI Trunked Subscribers and P25 Phase 1 CAI Trunked Infrastructure in manufacturer issued SDoCs (Supplier’s Declarations of Compliance) and STRs (Summary Test Reports) as part of the DHS Compliance Assessment Program.

In addition to the FDMA Common Air Interface, the Project 25 standard suite also enables interoperability for a TDMA Common Air Interface. The Project 25 suite of standards enables interoperability for several wireline interfaces including but not limited to the Inter-RF Subsystem Interface (ISSI) for connecting disparate P25 networks together which allows users to roam from one network to another network, have encrypted communications across the networks, and permits roamers to talk back with their home users. ISSI gateways are now commercially available in the marketplace today and recently in March 2010 interoperability testing was conducted by several manufacturers successfully demonstrating this capability.

The Project 25 suite of standards enables interoperability for several Data and Secure Services including but not limited to OTAR which provides for key management of encrypted voice and data communications regardless of radio or Key Management Facility manufacturer. Today there are multiple P25 Manufacturers offering commercially available OTAR solutions. Additionally many of these manufacturers have conducted preliminary interoperability testing for OTAR capabilities.