To improve line usage efficiency by maintaining a speech quality for satisfying a user and reducing a required amount of data for voice communication as compared with before.
An IP telephone terminal 100A comprises a statistical information collection circuit 112 for transmitting a statistical information collection packet to one's party, and recording/accumulating statistical information collected by the statistical information collection packet transmitted from one's party; a quality estimation circuit 113 for calculating the current speech quality based on statistical information recorded/accumulated by the statistical information collection circuit 112, and further estimating future speech quality from present speech quality; and a mode change circuit 114 for reporting the multiplicity of the coding system of a voice packet to one's party by messages, or the like according to the future speech quality estimated by the quality estimation circuit 113, determining the coding system and multiplexity of the voice packet, based on the statistical information sent from one's party, and indicating the coding system and multiplexity to a packetizing circuit 103 and a packet multiplexing circuit 104.
TAKAHATA TATSUMI
Ogata Japanese
Yasuo Takubo
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