A method for call establishment, comprising: obtaining a pre-configured binding relationship between a calling conference room and terminals in the calling conference room and between a called conference room and terminals in the called conference room, through a register server which receives a call request to require establishing a call between a calling terminal in the calling conference room and a called terminal in the called conference room, where the called terminal is determined to belong to a number group having the pre-configured binding relationship; setting correspondences between terminals of calling and called conference rooms according to the binding relationship, wherein any two terminals located at the same position in the calling conference room and the called conference room have a correspondence; sending a notification to non-calling terminals of the calling conference room, according to the binding relationship, wherein the notification carries the correspondences; and establishing media communications with the terminals having the correspondences by: establishing a call between each terminal of the calling conference room and a corresponding terminal of the called conference room according to the correspondences, respectively, establishing media channels in a call link of each call between each terminal of the calling conference room and the corresponding terminal of the called conference room, and performing media communication between each terminal and the corresponding terminal by transmitting a media stream between each terminal and the corresponding terminal via the media channels. obtaining a pre-configured binding relationship between a calling conference room and terminals in the calling conference room and between a called conference room and terminals in the called conference room, through a register server which receives a call request to require establishing a call between a calling terminal in the calling conference room and a called terminal in the called conference room, where the called terminal is determined to belong to a number group having the pre-configured binding relationship; setting correspondences between terminals of calling and called conference rooms according to the binding relationship, wherein any two terminals located at the same position in the calling conference room and the called conference room have a correspondence; sending a notification to non-calling terminals of the calling conference room, according to the binding relationship, wherein the notification carries the correspondences; and establishing media communications with the terminals having the correspondences by: establishing a call between each terminal of the calling conference room and a corresponding terminal of the called conference room according to the correspondences, respectively, establishing media channels in a call link of each call between each terminal of the calling conference room and the corresponding terminal of the called conference room, and performing media communication between each terminal and the corresponding terminal by transmitting a media stream between each terminal and the corresponding terminal via the media channels.