A method and system for preventing muting of ongoing services when a new multicast traffic channel, MTCH, is to be started or stopped are disclosed. According to one aspect, embodiments provide a method that includes sending an indication of service start to trigger sending of a multicast control channel, MCCH, update during a first MCCH modification period to inform the base station of the new MTCH to be started during a second MCCH modification period at a time determined at the base station. The method further includes sending control packet data units, PDUs, during an MCCH modification period preceding the second MCCH modification period, the PDUs arranged to avoid muting of the ongoing services.