A method and user equipment in a mobile telecommunications system for conducting a multimedia broadcast/multicast service (MBMS) session. An MBMS-uplink channel is introduced for transmitting from the user equipment, MBMS participation requests prior to the session and acknowledgment messages when MBMS messages are received. Relevant charging information is collected from the user equipment using broadcast/multicast services when an acknowledgment message is received. The telecommunication system then sends a decoding key to the user equipment for decoding at least a part of the data that is broadcast by the MBMS service.