Access stratum manager

A multi-mode mobile communication device for use in a plurality of wireless access networks, the multi-mode mobile communication device being operable to establish a communication link with a core network over a first wireless access network and transfer the communication link from the first wireless access network to a second wireless access network, comprising:

• a first access module operable to communicate over the first wireless access network;
• a second access module operable to communicate over the second wireless access network;
• a non-access stratum (NAS) module operable to communicate using a protocol compatible with the core network;
• an access stratum manager (ASM) module that interfaces the NAS module with the first and second access modules;
• the ASM module being operable to establish the communication link between the NAS module and the core network using the first access module;
• and
• the ASM module being further operable to maintain the communication link between the NAS module and the core network while transferring the communication link from the first access module to the second access module;
• wherein the multi-mode mobile communication device measures the respective signal strengths of the first wireless access network and the second wireless access network, and the ASM module initiates the transfer of the communication link from the first access module to the second access module in response to a handover control signal generated by first access module in response to the measured signal strengths.