System and method for instant message transmission in mobile communication terminal

An instant messaging method in an instant messaging system where two instant messaging systems of different types interwork, the instant messaging method comprising the steps of:

• a sender mobile communication terminal connected to one of the tnvo instant messaging systems generating an instant message delivery report request to a recipient mobile communication terminal connected to the other instant messaging system;
• converting the delivery format of an instant message into another suitable for the other instant messaging system and delivering the instant message to the recipient mobile communication terminal;
• upon completion of the delivery of the instant message to the recipient mobile communication terminal, generating an instant message delivery report including information about the receipt status of the instant message by the recipient mobile communication terminal;
• and
• converting the delivery format of the instant message delivery report to another suitable for the system to which the sender mobile communication terminal is connected and sending the instant message delivery report to the sender mobile communication terminal.

An instant messaging system in which an Interpersonal Messaging Service (IMPS) system and a Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIP/SIMPLE) system interwork, the instant messaging system comprising:

• an IMPS server for delivering an instant message according to IMPS;
• an SIP/SIMPLE server for delivering the instant message according to SIP/SIMPLE;
• a first mobile communication terminal included in a service coverage of the IMPS server;
• a second mobile communication terminal included in a service coverage of the SIP/SIMPLE server;
• and
• an interworking server for, if one of the mobile communication terminals generates an instant message delivery report request to the other mobile communication terminal in the delivery of the instant message, converting the delivery format of the instant message received from a server of a sender mobile communication terminal into another suitable for a system including a recipient mobile communication terminal, delivering the instant message to a server of the recipient mobile communication terminal, collecting an instant message delivery report including information about the receipt status of the instant message by the recipient mobile communication terminal upon completion of the delivery of the instant message to the recipient mobile communication terminal, converting the delivery format of the instant message delivery report to another suitable for a system including the sender mobile communication terminal, and sending the instant message delivery report to the server of the sender mobile communication terminal.