A subscriber accommodating apparatus (103, 113) which receives a SIP session connection request from at least one subscriber terminal (101-1, 101-2, 111-1, 111-2) to be transmitted to a SIP server (105, 115) installed in a voice control network (106, 116), comprising: discrimination and calculation means (303, 304) for discriminating the SIP session connection request and counting a number of SIP sessions under connection; comparison means (351, 352) for comparing the number of SIP sessions under connection with a first threshold value for detecting congested state of the SIP server and a second threshold value that is greater than the first threshold value for detecting the congested state of the voice control network and outputs a comparison result; and switch and transfer means (353, 306, 307, 308) for controlling a transfer of said SIP session connection request according to said comparison result; wherein when said comparison means determines that said number of SIP sessions is smaller than said first threshold value, said switch and transfer means (353, 306, 307, 308) transfers said SIP session connection request to the SIP server, when said comparison unit determines that said number of SIP sessions is greater than said first threshold value and smaller than said second threshold value, said switch and transfer means (353, 306, 307, 308) transfers said SIP session connection request to a media server, which can be directly accessed by said subscriber accommodating apparatus without accessing said SIP server, by converting header information of said SIP session connection request into a header address to said media server, and when said comparison unit determines that said number of SIP sessions is greater than said second threshold value, said switch and transfer means (353, 306, 307, 308) prohibits transferring said SIP session connection request to said SIP server and makes a SIP session response means (311, 312) transmit a predetermined information indicating the congested state in said SIP server and said voice control network to the subscriber terminal which transmitted said SIP session connection request. discrimination and calculation means (303, 304) for discriminating the SIP session connection request and counting a number of SIP sessions under connection; comparison means (351, 352) for comparing the number of SIP sessions under connection with a first threshold value for detecting congested state of the SIP server and a second threshold value that is greater than the first threshold value for detecting the congested state of the voice control network and outputs a comparison result; and switch and transfer means (353, 306, 307, 308) for controlling a transfer of said SIP session connection request according to said comparison result; wherein when said comparison means determines that said number of SIP sessions is smaller than said first threshold value, said switch and transfer means (353, 306, 307, 308) transfers said SIP session connection request to the SIP server, when said comparison unit determines that said number of SIP sessions is greater than said first threshold value and smaller than said second threshold value, said switch and transfer means (353, 306, 307, 308) transfers said SIP session connection request to a media server, which can be directly accessed by said subscriber accommodating apparatus without accessing said SIP server, by converting header information of said SIP session connection request into a header address to said media server, and when said comparison unit determines that said number of SIP sessions is greater than said second threshold value, said switch and transfer means (353, 306, 307, 308) prohibits transferring said SIP session connection request to said SIP server and makes a SIP session response means (311, 312) transmit a predetermined information indicating the congested state in said SIP server and said voice control network to the subscriber terminal which transmitted said SIP session connection request.