The present invention provides a method and system for supporting an optimized an idle mode handoff of user equipment from a 3GPP (EUTRAN) to a non-3GPP system (HRPD, cdma2000) where the user equipment washes to maintain connectivity with multiple PDN networks. Namely, during an idle mode registration of the user equipment with the non-3GPP system, the user equipment will provide an indication to the access node on the non-3GPP system so that the access point in that non-3GPP system contacts the appropriate entity (HSS or AAA) on the home network for the user equipment to download the addresses of the multiple PDN gateway addresses that are currently in use by the user equipment. This indication to the non-3GPP access node, the contact message from the access node to the home network, and the response from the home network to the access node on the non-3GPP system are novel features that are not shown in the prior art, and provide the access node with sufficient information to maintain multiple PDN connectivity to the user equipment during an idle mode handover.