North Fulton Regional Radio System Authority (NFRRSA), Hall County Regional Radio System (HCRRS) and Cobb Regional Radio System (CRRS) have created an Inter RF Subsystem Interface (ISSI) link that allows users of certain NFRRSA, HCRRS and CRRS talk groups to automatically roam onto the other's system in certain areas where the primary system has weak coverage but the partner system has strong coverage. A temporary talk group on the partner system is automatically assigned and linked back to the user's home talk group on the primary system. On the CRRS system, talk groups in 40,000 range are part of a pool of talk groups that are automatically randomly assigned by the CRRS for these temporary ISSI links to home systems talk groups on an as-needed basis, with no user, dispatcher or system administrator intervention required.