In a mobile communication
system, a host mobile communication terminal transmits an invite message to a
client mobile communication terminal by means of a short message, and the host mobile communication terminal and the
client mobile communication terminal perform a mutual messenger service through a PDSN, such that a
system for the messenger service may be easily constructed and a message may be quickly transmitted. Further, a host mobile communication terminal and
client mobile communication terminals each perform a point-to-point protocol connection with a PDSN, and perform a mutual messenger service, such that they can exchange data having various formats, such as text messages, audio information, and data / image information stored in the terminal with each other.