Communication service unit and connection sequence operating method

Abstract

Communication is performed without paying attention to the fact that the communication is executed between multimedia terminals having communication procedures differing from each other. A terminalstarts a communication procedure that is necessary to establish a communication path to a communication service unit, in order to execute communication with a multimedia terminal; when a communication protocol conversion unitreceives communication start request from the terminal, the communication service unit executes identification process of a calling terminal based on the identification number, which exists in communication start request, for determining the multimedia terminal, and inquires a terminal information managing unitof the calling terminal. The terminal information managing unitretrieves terminal information related to the calling terminal based on a terminal information request, and informs of the retrieved terminal information to the communication protocol conversion unit. The communication protocol conversion unitinforms of the communication start request to the terminalwhen the transmitting the terminal information of the terminalis obtained, and continues a relay process in communication procedure, which is necessary for following establishment of a communication path.