A quality of service session is established between a correspondent node and a mobile node. The mobile node has a home address in a home network is temporarily connected at a care-of address in a foreign network. A modified reply message is generated in the foreign network. The modified reply message has a source address of the mobile node's care-of address and a destination address of the correspondent node. The modified reply message is then transmitted. A capable of supporting such a quality of service session is also disclosed.