Question: What triggers the establishment of bearer resource for MBMS (Multimedia Broadcast/Multicast Service) data transfer in a telecom network?
Option 1: Session Start, when the BM-SC (Broadcast Multicast Service Centre) is ready to send data
Option 2: User Equipment (UE) activation of the MBMS service
Option 3: Completion of multicast session definition as per TS 22.146
Option 4: Initiation of multiple MBMS bearer services by the UE
Explanation: The correct answer is Option 1 because, according to telecom network protocols for MBMS, the Session Start - the point at which the BM-SC is ready to send data - serves as the trigger for establishing the necessary bearer resources. This is crucial for facilitating the transfer of MBMS data, highlighting the importance of Session Start in the operational flow of MBMS services.