A telecommunication system and a method for transferring media data from a first client over a QoS-sensitive network to a second client. The system and method can permit media data, which contain a first media type with a first traffic class and a second media type with a second traffic class to be bundled by the first client into second packets. In each second packet, the traffic class for each media type is marked in layer 4 and/or layer 5. The second packets can be transmitted toward the second client. Either before or during the transfer to the network, the second packets can be unbundled using the markings in layer 4 and/or layer 5 and then bundled into first packets, each of which has only one of the traffic classes. At least some of the first packets can then be transmitted over the network to the second client.