Chatting service method interworking video phone service

A chatting service method interworking with a video phone service in a mobile communication system capable of using a video phone service, the method comprising the steps of:

• initiating a video phone call between a first mobile communication terminal and a second mobile communication terminal;
• transmitting, by a mobile switching center (MSC), chatting service subscription confirmation messages to the first mobile communication terminal and the second mobile communication terminal, which are participating in the video phone call;
• if a chatting service request signal is input to the first mobile communication terminal, confirming whether the first mobile communication terminal is available for a chatting service interworking with a video phone service by checking the chatting service subscription confirmation message transmitted from the MSC;
• if the chatting service is available, transmitting, by the first mobile communication terminal, a chatting service request message through the MSC to the second a mobile communication terminal;
• confirming whether the second mobile communication terminal is available for the chatting service by checking the chatting service subscription confirmation message transmitted from the MSC;
• transmitting the confirmation result to the first mobile communication terminal;
• and
• if the second mobile communication terminal is available for the chatting service, transmitting, by the second mobile communication terminal, a chatting service response message through the MSC to the first mobile communication terminal to initiate the chatting service interworking with the video phone service.