Like any trunked system, LTR MultiNet allows users to be grouped to virtual channels on a system backbone. The system backbone consists of repeaters configured to support the LTR protocol. The virtual channels, called "system" and "group", are controlled by the system electronics. In an LTR system, the electronics that set up communications between radios are housed in each radio set, (scan-based). The MultiNet system has some form of central controller in addition to the scan-based radio electronics. When idle, radios scan all system channels searching for a valid system-and-group call. When a valid call is detected, all radios set to the detected "system" and "group", (virtual channel) meet on a physical channel and can communicate. A valid call could be an individual call or a call to a group of radios.