From the user perspective a Talkgroup is similar to a radio channel, all users who have selected a particular Talkgroup can hear (subject to access rights) all transmissions on that Talkgroup .
Users on a specific talkgroup do not have to be on the same radio site, the system will transmit the Talkgroup traffic wherever an authorised radio has that Talkgroup selected.
Talkgroups can be joined (or patched) in different ways so that different user groups can monitor relevant activities. Dispatcher, PABX and PSTN telephone users can join a Talkgroup if required.
From a system viewpoint an inactive talkgroup does not occupy any resources as radio channels/timeslots are only allocated when a user presses their transmit key and are released after a preprogrammed period of inactivity.
Talkgroups are defined as part of the Fleetmapping activity.