Abstract: When a call session is set over an IP network between a calling IP phone and a called IP phone at the start of a call, information on the quality of communication between a host IP phone and a recording server is exchanged to compare the quality of communication of the two IP phones in each of the calling IP phone and the called IP phone. For example, the called IP phone, or a host IP phone, with a higher quality of communication than the calling IP phone of a conversing party transmits call audio data to the recording server as recording data. Meanwhile, the calling IP phone, or a host IP phone, with a lower quality of communication than the called IP phone of a conversing party refrains from transmitting the call audio data to the recording server.

Abstract: When a call session is set over an IP network between a calling IP phone and a called IP phone at the start of a call, information on the quality of communication between a host IP phone and a recording server is exchanged to compare the quality of communication of the two IP phones in each of the calling IP phone and the called IP phone. For example, the called IP phone, or a host IP phone, with a higher quality of communication than the calling IP phone of a conversing party transmits call audio data to the recording server as recording data. Meanwhile, the calling IP phone, or a host IP phone, with a lower quality of communication than the called IP phone of a conversing party refrains from transmitting the call audio data to the recording server.