Multicast/broadcast messaging service (MBMS) arrangement, in which a broadcast/multicast service center delivers multimedia messages to a plurality of users via a gateway GPRS support node (GGSN) and via a serving GPRS support node (SGSN) and a radio access network (RAN), in association with a given temporary mobile group identity (TMGI) and using a single radio access bearer (RAB). Responsive to a given event, the SGSN sends to the RAN a data volume report query identifying said RAB by the TMGI or another unique parameter. The RAN responds with a data volume report that indicates the amount of unsent MBMS data. If so agreed, the SGSN will pass said amount to a charging gateway for compensation in charging for the MBMS service.