Improvements in handover between heterogeneous radio networks

Disclosed is a method of performing a handover of a mobile device from a first wireless IP network to a second wireless IP network, the mobile device being connected, via a tunnel, to a Server of a Mobile IP system, and to an information server coupled to the first and second wireless networks, wherein the information server is arranged to provide handover messages to the mobile device to assist the mobile device in performing a handover from the first wireless network to the second wireless network, comprising the steps of: determining that a handover is imminent or in progress and transmitting data packets to the mobile device from the server and also buffering the data packets containing handover messages at the server if the handover is in progress. Data packets containing application data may also be buffered while handover is imminent or in progress.