Method for performing handover between different radio system and providing information thereof using voice call

PURPOSE: A handover performing method between heterogeneous wireless systems and method thereof are provided to supply wireless base station information through an originator identification number of a mobile communication network. CONSTITUTION: A wireless terminal(210) receives an incoming voice call for a heterogeneous network search trigger including information about connectable heterogeneous network wireless base station from a server. The wireless terminal confirms an originator telephone number as a specific originator number for the heterogeneous search trigger(542). The wireless terminal turns on a heterogeneous wireless network modem(544). The wireless terminal searches for the connectable heterogeneous wireless base station(546). The wireless terminal performs a handover between heterogeneous wireless networks(552).