System and method for preventing first call loss on mvoip

PURPOSE: Mobile voice over internet protocol (mVoIP) terminal first call loss prevention system and prevention method thereof are provided to prevent the loss of the first called call of a receiving request call while an mVoIP terminal is in an unregistered state. CONSTITUTION: An mVoIP terminal (13) receives a location registration result signal of a VoIP switch. The mVoIP terminal provides Keep Alive notification to a mobile keeper (14). The mobile keeper receives a Keep Alive signal of the location registration result of the mVoIP terminal. The mobile keeper transmits an automatic call transfer request signal to the VoIP switch. The mobile keeper transmits a signal showing that a call of an IP subscriber is inserted into the mVoIP terminal. The mobile keeper sets up a call path according to a hook-off signal of the mVoIP terminal to make a normal call. [Reference numerals] (10) VoIP switchboard; (12) IP phone; (13) Wireless VoIP terminal; (14) Mobile keeper