in order to assist an exchange of data between one or mobile communications devices and the internet in a mobile communications network , bidirectional tunneling of ipv6 messages inside ipv4 messages is performed between a home agent and one or more foreign agents . optionally , where a mobile communications device is a wireless mobile unit , the mobile unit itself automatically engages in bidirectional tunneling of ipv6 messages inside ipv4 messages with the home agent whenever the wireless mobile unit detects loss of wireless coverage in the mobile communications network and presence of coverage in a type of wireless network lacking foreign agent functionality .