A mobile station includes a voice mail password in an outgoing call message for a call, a data communication and the like. A mobile telephone switching center determines whether the voice mail password of the outgoing call message from the mobile station is consistent with the voice mail password from the voice mailing system, and provides the call service to the corresponding mobile station when they are consistent with each other. The voice mail password can be registered or changed after the user connects to the voice mailing system and is identified for the voice mail service. Therefore, the user can just merely change the voice mail password, thereby preventing unauthorized use of the mobile station.