System for packet data service in the mixed network of asynchronous communication network and synchronous communication network and hand-over method thereof

Disclosed herein is a mobile communication terminal and handover method therefor, which enable handover of a mobile communication terminal that is using a packet data service or is in a dormant state in a mobile communication network in which asynchronous and synchronous networks coexist. In the handover method, if a channel is assigned between a mobile communication terminal and a synchronous mobile communication system in response to a request from an asynchronous mobile communication system as a mobile communication terminal using packet data service in the asynchronous mobile communication system moves into an area of the synchronous mobile communication system, call setup is performed. A node B of the asynchronous mobile communication releases a connection to the mobile communicationsystem and assigns a new mobile IP to the mobile communication terminal, thus providing continuous packet data service to the mobile communication terminal.