Techniques for performing inter-system handover are described. An Access
Gateway (AGW) sends a message requesting handover of a user equipment
(UE) from a first radio access network (RAN) to a second RAN. The message
is sent to an Inter Access System (inter-AS) Anchor for the first RAN
communicating with an SGSN for the second RAN via a Gn interface. The
Inter-AS Anchor and SGSN exchange messages via the Gn interface, and the
Inter-AS Anchor forwards the messages to the AGW to handover the UE from
the first RAN to the second RAN. The SGSN sees the Inter-AS Anchor as
another SGSN for the handover and as a GGSN after the handover. This
allows the inter-system handover to be achieved with an inter-SGSN SRNS
relocation procedure used for handover between two SGSNs, which reduces
impact on the SGSN to support the inter-system handover.