Zetron Multisite Gateway Multi-Site Network Gateway for P25 Zone Coordination and Inter-Agency Talk Group Bridging

The Zetron Multisite Gateway is the multi-site network gateway designed for the interagency operations center that coordinates communication between agencies operating P25 networks from different manufacturers — National Police on their Motorola P25 network, Fire Department on their Kenwood P25 network, Municipality on their Harris P25 network — and that need the head of CODISEC (District Citizen Security Committee) or COE (Emergency Operations Center) operations to speak with talk groups from any of these networks simultaneously, without network users needing to modify their radios or operating procedures.

The P25 ISSI (Inter-RF Subsystem Interface) protocol implementation allows the gateway to act as an RFSS zone server connecting up to 32 zones from different P25 networks in real time, routing each talk group's audio traffic with latency under 20 ms — imperceptible in voice communications — and maintaining P25 signaling information (radio ID, talk group, call priority, emergency status) across network boundaries, so the transmitting Police officer's radio identifier appears correctly on the Communications Center dispatcher's screen even though the radio is registered on a different P25 network.

The configurable call priority system allows assigning priority levels 1-15 by hierarchical rank (commissioner, captain, officer) and by agency (PNP, Fire, SAMU), ensuring that in network congestion situations the system routes higher-priority radio audio first and defers lower-priority audio without audio loss — with automatic queue wait alerts to the held radio — implementing the P25 Phase 2 CAI (Common Air Interface) call priority protocol in the gateway without modifying connected network firmware.