Ericsson KDDI Lab Alcatel-Lucent UC3M Proxy Mobile IPv6 (PMIPv6) is a network based mobility management protocol that enables IP mobility for a host without requiring its participation in any mobility-related signaling. While the PMIPv6 protocol itself supports handover across interfaces and between access types, there are several issues with effectively performing inter-technology handovers with network based mobility protocols. This document aims to enumerate some known issues with such handovers.