Method of realizing business type change

This invention discloses a method for realizing change of service kinds in the period of session, in which, a terminal actively starts the change of the service kinds, therefore, it can realize the change of service kinds even if switch happens among MSC and the terminal can automatically adjust the service based on the support to services by networks, that is to say terminals can not only start the change of retreating to the phone service from the video service but also change the phone service to video service not needing the active intervention of users.