Method for calling video communication service by video communication terminal and associated message data form

A method for calling video communication service by video communication terminal, wherein at least one multipoint control unit (MCU) connects with video communication terminals through a IP network, is characterized that comprising the steps of:

• (a′) establishing a channel with an IP network gate keeper (GK) by a first video communication terminal and sending to the GK needed conference information for convening a conference;
• (i′) retransmitting the conference information to a service management center by the GK;
• dispatching resources of related MCUs by the service management center;
• sending the conference information to the related MCUs and instructing the MCUs to convene the conference by the service management center;
• (b′) convening the conference by the MCUs, according to the conference information received.

The method according to claim l7, further comprising the steps of:

• (f) after authentication, sending a control connection request to a MCU by a video communication terminal of the conference through the In-Band channel between the video communication terminal and the MCU;
• receiving or rejecting the control connection request by the MCU;
• (g) if in step (f), the control connection request is received, sending one or more than one conference control requests to the MCU through the In-Band channel by the video communication terminal;
• (h) making response of conference control requests from the video communication terminal by the MCU.