Section: 19.2.1.2 Service Provided by the BM-SC in visited PLMN
Content: When visited and home PLMN support the same classes of MBMS user services, a visited PLMN may offer its own MBMS user services to roaming users. In this case, the authorization is done in the BM-SC in visited PLMN with the authorization information retrieved from the BM-SC in home PLMN. Then the MBMS user traffic is provided by the BM-SC in visited PLMN. Figure 29a: Activation of an MBMS multicast service in roaming scenario with service provided in the visited PLMN 1. The GGSN sends an AAR to the BM-SC in visited PLMN seeking authorizationt information for the activating roaming UE to receive data from a particular service. 2. The BM-SC in visited PLMN finds the BM-SC in home PLMN which have the authorization information for the roaming UE based on the multicast IP address, and identity of the user, and sends the AAR to it for the roaming UE to receive authorization from a particular service. 3. The authorization decision is provided from BM-SC in home PLMN in the AAA to BM-SC in visited PLMN. 4. The authorization decision, as received from BM-SC in home PLMN, is provided in the AAA to GGSN together with the APN to be used for creation of the MBMS UE Context If the AAA indicates that the roaming UE is not authorized to receive the MBMS data the process terminates with no additional message exchange. 5. The GGSN sends an AAR seeking authorization for the activating UE to BM-SC in visited PLMN. This GGSN may be different from the GGSN that receives IGMP join message. 6. The authorization decision is provided in the AAA to GGSN.