Radio Resource Magazine: OnlyOnline
(only some of the article provided below)
Several jurisdictions are looking to integrate the latest version of the Project 25 (P25) Inter Subsystem Interface (ISSI) into their statewide networks. Officials said the latest versions of ISSI products include more functionality and are easier to use than original versions.
The ISSI standard, first commercially implemented in 2010, aims to connect disparate P25 networks, regardless of vendor. For example, an ISSI gateway could connect a standalone Motorola Solutions P25 network to a Harris P25 network.
ISSI technology has not been widely deployed for various reasons including cost, complicated manual management and roaming from one P25 system to another, and lack of a Compliance Assessment Program (CAP) for the ISSI standard.
The state of Missouri plans to deploy Motorola’s ISSI 8000 system interface later this year to connect its statewide P25 VHF/700 MHz network to the Kansas City (Missouri) Police Department 800 MHz system, which is part of the Metropolitan Area Regional Radio System (MARRS). Motorola supplied both networks, and the upgrade requires both jurisdictions to have Motorola’s system 7.13 or a later version.
In July, the state of Missouri and the Kansas City Police Department are upgrading their P25 systems to 7.14 software. The ISSI packet gateway will be added to each system’s master site.
“ISSI.1 was an interim solution,” said Steve Devine, assistant director for the Missouri Statewide Interoperability Network (MOSWIN). “It wasn’t anyone’s perfect solution. It allowed baseband audio to be passed between systems, and roaming between systems required a knob change; there was no seamless transition between the systems. But it provided limited intersystem interoperability when implemented. It wasn’t a tool that made intersystem connections and roaming between systems easy from a system administration perspective but it did provide interoperability. Then the goal was to come up with a better ISSI, and that’s what we’re seeing in ISSI 8000.”
Devine said the updated ISSI is much easier to manage than the original product. A system administrator can pre-determine the parameters — unit IDs, talk groups, talk paths and sites — for one network’s users to have access to the other network. The update also includes an option to allow seamless roaming for users, removing the need for users to turn a knob on their radios to move to a neighboring radio system.