Apparatus and method by which Internet Protocol (IP) traffic can be transferred (i.e. handoff) between two different terminals operating according to two different technology standards in two different systems with two different IP addresses. For example, a session handoff can be made between a terminal in Wireless Local Area Network (WLAN) a terminal in a 3GPP UMTS or between a terminal in CDMA2000 and a terminal in a 3GPP UMTS. These terminals can be either physically separate entities or logical entities that are encapsulated within a common enclosure.