Patent ID: 8576763

Claim:
A method for distributing multicast data of a multicast service to different domains each controlled by a different Push-to-talk Over Cellular Application Server, PoC AS, the method comprising the following steps performed by PoC AS, of a first domain of the different domains: receiving from a client in the first domain a service initiation request for setting up the multicast service between a plurality of service participants, wherein the service initiation request identifies the plurality of service participants that are to participate in the multicast service, identifying, based on the identification of the plurality of service participants, the domains to which the plurality of service participants belong and that are not controlled by the PoC AS of the first domain, and distributing the multicast data to the PoC ASs of the identified domains on a per-domain basis, wherein the distributing of the multicast data to the PoC ASs of the identified domains comprises distributing a single copy of the respective multicast data via a point-to-point link to a PoC AS of a respective domain for further distribution to the service participants in the respective domain.