Abstract: In a trunked communication system with at least two communication sites, a call hand-off mid-call may occur when a mobile radio (109) moves from the coverage area of one site to the coverage area of another site. This second site may not have any communication resources available for this hand-off, and the radio (109) is issued a busy message. With user selectable site switching, the user may enter into the radio (221) the desire to return to the previous site, and the radio moves to the previous channel to continue (229) receiving the call.

Abstract: An enhanced talkgroup scanning algorithm is provided. This algorithm provides an efficient scan function when a unit scan list contains a mixture of trunked talkgroups and conventional channels. This is accomplished by adding a new scanning algorithm for conventional priority groups, and by enhancing the trunking talk group scanning cycle. A novel scanning algorithm for conventional priority groups is used to decrease the audio holes in trunking calls when looking back at a priority conventional channel. When a unit is active on a low priority trunking call and goes over to the priority conventional channel to check for activity, several new steps are taken into consideration when the unit goes back to the trunked system/active trunked call. Based on whether there has been activity on the priority channel, the unit will immediately return to the old voice channel (unsquelched) or revert to the control channel.

Abstract: A typical multi-site trunked communication system comprises communication units that are arranged into talk groups, communication resources distributed among communication sites, and a communication resource allocator. In such a system, a methodology is incorporated that allows communication units to override communication site busy conditions, where the communication site busy conditions prohibits placement of group calls until all communication sites have an available communication resource. The communication site busy condition may be overridden by a communication unit by initiating a busy override signal. Once the busy override signal is initiated, the communication resource allocator allocates, in each site, a communication resource to the communication group of the requesting communication unit.