A method of controlling the operation of a communication system is described, where the system comprises a first entity 2 for sending a first data object 21 to a terminal device 4 and a second entity 3 for sending a second data object to the terminal device at the request 41 of the terminal device 4. The communication system also comprises a data transfer entity 11 and a charging entity 5. The data transfer entity 11 records charging relevant parameters related to the transfer of the first data object. It is proposed that the second entity 3 is controlled to output a predetermined triggering message to the data transfer entity 11 and/or charging entity 5, where the operation of processing the charging relevant parameters in a charging procedure is postponed until the predetermined message is received.