DETERMINING AVAILABILITY OF MEMBERS OF A CONTACT LIST IN A COMMUNICATION DEVICE

摘要

A method of determining PTT availability of members of a contact list in a wireless PTT communication system makes efficient use of resources by updating client devices (118, 122, 126) with new PTT contact list status information only when necessary. The availability of client devices (118, 122, 126) associated with contact lists (528, 530, 532) are determined by a PTT controller (112) according to the content of messages from the client devices (118, 122, 126). New information regarding the availability of a client device associated with a contact list (528, 530, 532) is transmitted to relevant client devices (118, 122, 126) only when a change has occurred in the availability of a member. Likewise, a client device (118, 122, 126) notifies the PTT controller (112) of its availability only when a change occurs.