Selecting an appropriate PDP context at a GPRS gateway support node for transferring a data packet from a mobile node to a correspondent node

A GPRS gateway receives a tunnelled data packet from a mobile node MN in a home network and selects a channel for transferring the packet to a correspondent node CN by mapping a PDP address (home address) used by the MN to one or more data packet filters associated with the channels. When the MN roams to a foreign network it is assigned a care of address CoA which is not recognised by the gateway. Therefore the first data packet sent by the MN from the foreign network includes the PDP address used by the MN in the home network. The CoA is then included in the data packet filters.