Abstract: In a trunked communications network, a multiple site information distribution control "switch" (multisite switch) provides access to digitized audio and control signals from various audio sources to one or more audio destinations connected at various "nodes" in the multisite switch. A dedicated Network Interface Module (NIM) is provided in the multisite switch to facilitate interconnection and communication between multiple networks of similar multisite switch controlled architectures to create an "extended" mega-network. The NIM allows an entire remote network to appear as a just another multisite switch node in a local network and vice versa. A trunked communications network having a NIM can communicate through this "node" with other networks having a NIM, thus establishing inter-network communications in a manner that is essentially transparent to users in either network.

Abstract: A method for resolving talk group call contention in a multi-site trunked radio frequency communications network is accomplished in a distributed manner by utilizing autonomous call arbitration processes at each interface node to avoid potential performance bottlenecking and a "single point of failure" configuration that would arise in a conventional centralized arbitration arrangement. Call contention in a multi-site environment occurs when multiple callers at different sites attempt to transmit on a common talk group at nearly the same moment. The call processing system that coordinates communications between sites must resolve this contention to ensure that the transmission is processed consistently at all sites. In accordance with the distributed manner of the present invention, each site interface autonomously determines which call should be given priority in a contention situation based upon a predetermined common set of arbitration "rules".

Abstract: In an extended overall radio communications network, one or more dedicated Network Interface Modules (NIMs) are provided in each multisite trunked communications systems to permit the interconnection and communication between plural, multisite systems. A remote multisite system appears through the local NIM as just another site interface to the local multisite system. Basic and advanced dispatch console functions are effected over the extended network via the NIMs in a manner that is transparent to the console operator.

Abstract: A RF site link for communicating between a centralized switching system and a plurality of mobile communications RF base stations is disclosed. The RF site link includes a plurality of RF link devices connected to centralized switching equipment. The RF link devices transmit signals to and receive signals from the remote base stations over the same working channels that the base stations use to communicate with the mobile or portable radios within each of the base stations' areas of operation. A RF control link is provided to control the assignment of the working channels between the centralized switching equipment and each of the base stations within the system.