of the traffic two independent schemes will now be described the first scheme involves data stream identification based on gprs tunnelling protocol identification gtp tid and operates as follows after being informed the established voip traffic path transport addresses the sgsn 34 identifies the two tids gtp tunnel id corresponding to the uplink and downlink traffic path for the established voip session then the sgsn 34 can control rnc 24 and the local mgw via a media gateway controller to handle the media traffic specially in an optimised way which is described below for uplink traffic handling the sgsn 34 informs rnc 24 the gtp tid which is the tunnel id for the uplink traffic of the voip session the rnc 24 obtaining this tid then can handle the traffic arriving from a particular rab that is associated with the tid the traffic handling for this rab is as follows shown in fig6 a voip packet 50 arrives at the rnc from the mobile station 22 via a node b as normal for each packet the rnc 24 strips off the l1 and l2 headers and gets the user level ip packet this user level ip packet will be routed towards the local mgw 28 using normal ip routing scheme as a result the l1 and.