A system and method for transmitting call information in a communication system having sites with long link delays. Upon a call being initiated within the communication system, a zone controller determines the participating sites that are to be involved in the call and assigns an IP multicast group address for the call. The zone controller also determines whether any of the participating sites have a long link delay. If any of the participating sites do have a long link delay, the zone controller also assigns an IP unicast address for each such site. The call information is then transmitted both on the IP multicast address as well as on each assigned IP unicast address to ensure that the call is received by each participating site without the loss of call information.