The invention relates to a mechanism for performing multicast transmission in a cellular network. In order to enable establishment of resources only in cells containing members of the multicast group and to avoid congestion on the uplink channel, a multicast service notification is transmitted to mobile stations, thereby informing members of the multicast group of an upcoming multicast session. The moment for a response to said multicast service notification is selected in the mobile stations and a presence report is sent from at least one of said mobile stations at the response moment of said at least one mobile station. The presence report or reports are received within a radio access network, and radio resources are established for multicast transmission in a cell of the cellular network when the presence report(s) received in said cell meet(s) predetermined criteria.