Method and apparatus for managing messages thread in converged internet protocol messaging service

A method and a system for managing message threads in a CPMS(Converged IP(Internet Protocol) Messaging Service) are provided to offer the messages transmitted and received between a CPM(Converged IP message) user and an SMS(Short Message Service) user to them as a group at the same time so that the CPM user can effectively transmit and receive interactive messages without judging whether the SMS user's terminal supports the CPMS. A CPM client transmits a SIP message to an IWF(Interworking Function) through a CPM server, including a message to transmit and a thread ID(601,603). Receiving the SIP message(605), the IWF converts it into a proper short message, such as an SMS_SUBMIT PDU, and confirms whether the SIP message contains the thread ID(607,609). If the thread ID exists, the IWF extracts it and adds it to the converted short message(611). Then the IWF sends the short message to an SMSC(SMS Center)(613,615). The IWF transmits the short message to a mobile station through an SMS_DELIVER PDU(617). The mobile station transmits an SMS_DELIVER_REPORT PDU to the SMSC(619). The SMSC transmits an SMS_STATUS_REPORT PDU to the IWF(621). Receiving the SMS_STATUS_REPORT PDU, the IWF transmits a 200 OK message to the CPM client through the CPM server(623,625).