Best Practices for Planning and Implementation of P25 Inter-RF Subsystem Interface (ISSI) and Console Subsystem Interface (CSSI): Volume II July 2020

Federal Partnership for Interoperable Communications and the SAFECOM/National Council of Statewide Interoperability Coordinators have just published a new Best Practices Volume II for ISSI/CSSI Interoperability. This is a follow-on document to the previously published ISSI/CSSI Primer and the ISSI/CSSI Best Practices Volume I documents.

Links to the documents are available on the Safecom and PTIG Websites below:

ISSI/CSSI Best Practices for Planning and Implementation Vol II July 2020

Executive Summary:

Project 25’s (P25) accredited technical standards define features, functions, and the interfaces of P25-compliant radio systems. Two of these interfaces, the ISSI and CSSI, are designed to enhance the operability and interoperability of new and existing land mobile radio systems. ISSI technology permits multiple radio core systems or Radio Frequency (RF) subsystems to be connected and form larger wide-area networks, supporting the “system-of-systems” concept. The CSSI interface can provide interoperability among multiple dispatch console manufacturers’ and system infrastructure manufacturers’ console product offerings, which enables public safety agencies to implement third party P25 console systems.

Given increased interest in both ISSI and CSSI technology, the Federal Partnership for Interoperable Communications, supported by the Cybersecurity and Infrastructure Security Agency (CISA), established the ISSI/CSSI Working Group (comprised of users and manufacturers) and the Focus Group (users only) to explore the ISSI/CSSI technology environment. Among other topics, the Working Group and Focus Group continue to explore connecting single and multiple manufacturers’ ISSI or CSSI technology offerings; collect user and manufacturer implementation procedures and troubleshooting methods; and identify best practices and commonly identified implementation and operational challenges in an ISSI and/or CSSI environment.

This new Volume II document outlines additional categories for practitioners to consider when planning for and implementing ISSI or CSSI technologies. The high-level categories are rooted in best practices observed during all project phases by local, county, regional, and state agencies implementing ISSI/CSSI and are provided as a resource for others in the community who may be contemplating or proceeding with ISSI/CSSI implementation.

The six categories from both Volume I and the New Volume II are listed below:

Volume I

  • Pre-Planning – This category can include a nearly endless set of questions and topics to consider before planning and implementing an ISSI or CSSI, including articulating the underlying purpose, identifying potential partners, setting expectations, conducting a cost-benefit analysis, and pursuing education or training to sufficiently understand the technologies.
  • Partnerships and Governance – Governance is one of the critical success elements that must be addressed to achieve and maintain a sophisticated interoperability solution. This category includes establishing trusted relationships, expressing a desire to interoperate, solidifying partnerships, and establishing formal governance structures via documentation that addresses everything from roles and responsibilities to financial and budget considerations.

New Volume II

  • Stakeholders – It is critical to identify the “right” stakeholders to be involved in planning and implementation, including key leadership, radio systems provider personnel, network professionals, manufacturer personnel, consultants, technical experts, and end users.
  • Technology – The selection and implementation of offered technology solutions and associated features and functions presents many potential challenges that user agencies must understand and be prepared to address.
  • Policies – Partnering agencies must establish standard operating procedures and policies to address everything from talkgroup management to fleet mapping and from user protocols to software and hardware version controls.
  • Thinking Ahead – Throughout planning and implementation, agencies must constantly look ahead and plan for various elements, including continuing active coordination of operations and maintenance, future upgrades, and new or revised feature implementations