A SIP terminal control system in a system comprising a master main device and one or more slave main devices (102-1, 102-2) connected to the master main device, comprising: a plurality of multilink sections (205-1, 205-2, 205-3) which are included in the master main device, and are operated by using a CPU of the master main device, wherein one of the plurality of multilink sections corresponds to the master main device and the others of the plurality of multilink sections correspond to each of said one or more slave main devices, respectively; and a plurality of SIP terminal connecting sections, one of which is included in the master main device and the others of which are included in the slave main devices, and which are connected with one or more SIP terminals, wherein: the SIP terminal connecting section included in the master main device is linked with multilink section corresponding to the master main device through a SIP link, and the SIP terminal connection sections included in said one or more slave main devices are linked with the multilink sections corresponding to the slave main devices, respectively, through the SIP link, each of the SIP terminal connecting sections is operated by using a CPU of the master main device without using CPUs of the slave main devices if the SIP terminal connecting section is included in the master main device, and by using the CPU of the slave main device without the CPU of the master main device if the SIP terminal connecting section is included in the slave main device, and each of the SIP terminal connecting sections is connected, via the multilink section corresponding to the SIP terminal connecting section, to a package/terminal management module and an input/output control module which are included in the master main device to be controlled therefrom. a plurality of multilink sections (205-1, 205-2, 205-3) which are included in the master main device, and are operated by using a CPU of the master main device, wherein one of the plurality of multilink sections corresponds to the master main device and the others of the plurality of multilink sections correspond to each of said one or more slave main devices, respectively; and a plurality of SIP terminal connecting sections, one of which is included in the master main device and the others of which are included in the slave main devices, and which are connected with one or more SIP terminals, wherein: the SIP terminal connecting section included in the master main device is linked with multilink section corresponding to the master main device through a SIP link, and the SIP terminal connection sections included in said one or more slave main devices are linked with the multilink sections corresponding to the slave main devices, respectively, through the SIP link, each of the SIP terminal connecting sections is operated by using a CPU of the master main device without using CPUs of the slave main devices if the SIP terminal connecting section is included in the master main device, and by using the CPU of the slave main device without the CPU of the master main device if the SIP terminal connecting section is included in the slave main device, and each of the SIP terminal connecting sections is connected, via the multilink section corresponding to the SIP terminal connecting section, to a package/terminal management module and an input/output control module which are included in the master main device to be controlled therefrom. the SIP terminal connecting section included in the master main device is linked with multilink section corresponding to the master main device through a SIP link, and the SIP terminal connection sections included in said one or more slave main devices are linked with the multilink sections corresponding to the slave main devices, respectively, through the SIP link, each of the SIP terminal connecting sections is operated by using a CPU of the master main device without using CPUs of the slave main devices if the SIP terminal connecting section is included in the master main device, and by using the CPU of the slave main device without the CPU of the master main device if the SIP terminal connecting section is included in the slave main device, and each of the SIP terminal connecting sections is connected, via the multilink section corresponding to the SIP terminal connecting section, to a package/terminal management module and an input/output control module which are included in the master main device to be controlled therefrom.