Abstract: The present invention takes the advantage of the WLAN resources in hotspots for voice and data connections and enables seamless handover between WWAN and WLAN and vice versa. This allows two users in the hotspots to communicate with each other by making a voice over IP (VoIP) or video call, thus achieving cost savings for the end users and WWAN resources savings for the wireless operators. According to one embodiment of the invention, a mobile terminal has wireless wide area network (WWAN) and wireless local area network (WLAN) interfaces. The mobile terminal via a WWAN. If a WLAN is present, the mobile terminal sends a handover request together with its network address to the called mobile terminal, using a short message service (SMS) technique or a watermarking technique, for initiating a WLAN call with the called mobile terminal via a WLAN. After the WLAN call is established with the called mobile terminal, the mobile terminal releases the WWAN call.

Abstract: A communication method for a mobile terminal to perform seamless handover between a WWAN and a WLAN, comprising steps of: receiving a registration message sent by said mobile terminal when it enters said WLAN, wherein said registration message at least contains a WLAN address that said mobile terminal acquires when entering said WLAN; establishing the mapping relationship between said MAN address and said WLAN address of said mobile terminal according to said registration message; encapsulating said WLAN address into the data information to be sent to said mobile terminal according to said mapping relationship when receiving the data information to be sent to said mobile terminal from a source address; and sending the data information containing said WLAN address to said mobile terminal via said WLAN.