Patent attributes
A server (101) designates and assigns each of a plurality of communication devices to at least one of a plurality of groups. The server (101) prepares a communication having presence information corresponding to a status of the communication devices in the group; determines network infrastructure device(s) serving the group; and transmits, at a pre-determined time, the communication to the network infrastructure device(s). A network infrastructure device (103a-c, 105a-f) receives the communication and transmits, as a common channel signal during the pre-determined time, a signal with the presence information. A communication unit (107a, 107b, 107c) receives an indication of the pre-determined time; transmits, at an interval proximate to the pre-determined time, a signal indicating the communication device's status; and receives, at the pre-determined time, the signal with the presence information.
