Patent ID: 7986692

Claim:
A method for transmitting call information in a communication system between members of a talkgroup comprising: receiving a call request from a calling unit at a sourcing site; determining one or more participating sites for the call; determining that at least one of the participating sites is a long link delay site by at least: transmitting a first signal from a zone controller to the at least one of the participating sites, processing the first signal at the at least one of the participating sites, upon finishing processing of the first signal, transmitting a second signal from the at least one of the participating sites to the zone controller, the second signal including at least one of a time stamp indicating a transmission time when the second signal is transmitted from the at least one of the participating sites to the zone controller or an indication of a processing time for the at least one of the participating sites to process the first signal, determining at least one of a transmission delay time between transmitting the first signal from the zone controller and receiving the second signal at the zone controller or a reception time at which the second signal is received by the first zone controller, and determining whether at least one of the difference between the transmission and reception times or the difference between the processing and transmission delay times is greater than a preset link delay threshold; assigning a multicast group having a multicast group address for the call; identifying a unicast address for each long link delay site; transmitting a call grant signal to the sourcing site and each participating site, the call grant identifying the multicast group address and each unicast address identified for each long link delay site; transmitting the call information on the multicast group address; and transmitting a copy of the call information on each unicast address identified for each long link delay site.