Method and apparatus to efficiently support group call confirmation

A call information server in a two-way radio system, comprising:

• a network interface communicatively coupled to a plurality of subscriber units through infrastructure of the two-way radio system;
• a processor communicatively coupled to the network interface;
• and
• memory storing computer executable instructions, and in response to execution by the processor, the computer executable instructions cause the processor to perform steps of:
• access group list information associating a plurality of subscriber units with one or more groups, each group including a plurality of target subscriber units associated with the group for receiving a group call;
• receive, via the network interface, updates related to presence information setting forth whether each particular target subscriber unit in the group list information is online or offline and updates related to availability information setting forth whether each particular target subscriber unit in the group list information is busy on another call or is available for the receiving the group call;
• detect a request from an initiator subscriber unit for a particular group call to a particular group of a plurality of particular target subscriber units included in the group list information;
• and
• confirm, after call setup, for each of the plurality of particular target subscriber units indicated in the particular group, the particular target subscriber unit's participation or lack of participation in the particular group call, as a function of the updates related to presence information, the updates related to availability information, and the group list information and provide, after the group call, an indication of each particular target subscriber unit's confirmed participation or lack of participation in the particular group call to the initiator subscriber unit.

A two-way radio system, comprising:

• a plurality of subscriber units communicatively coupled to an infrastructure;
• and
• a call information server communicatively coupled to the plurality of subscribers via a network interface, wherein the call information server comprises memory storing computer executable instructions, and in response to execution by a processor, the computer executable instructions cause the processor to perform steps of:
• access group list information associating the plurality of subscriber units with one or more groups, each group including a plurality of target subscriber units associated with the group for receiving a group call;
• receive, via the network interface, updates related to presence information setting forth whether each particular target subscriber unit in the group list information is online or offline and updates related to availability information setting forth whether each particular target subscriber unit in the group list information is busy on another call or is available for the receiving the group call;
• detect a request from an initiator subscriber unit for a particular group call to a particular group of a plurality of particular target subscriber units included in the group list information;
• and
• confirm, after call setup, for each of the plurality of particular target subscriber units indicated in a particular group list as forming a particular group, the particular target subscriber unit's participation or lack of participation in the particular group call, as a function of the updates related to presence information, the updates related to availability information, and the group list information and provide, after the group call, an indication of each particular target subscriber unit's confirmed participation or lack of participation in the particular group call to the initiator subscriber unit.