Network node, terminal, bandwidth modification determination method and bandwidth modification method

摘要

The objective of the present invention is to suppress deterioration of call quality caused by transcoding without interrupting a call even if a codec used by one of the terminals during communication is changed. A modification determination unit, in the case of detecting a modification of a codec used by one terminal of two terminals, determines whether or not to constrain the bandwidth of the first codec using a first codec of the other terminal and a second codec after modification by the first-mentioned one of the terminals. A signaling generation unit transmits, to the other terminal, signaling for limiting the bandwidth if the bandwidth is to be limited.

主权项

1. A communication terminal apparatus, comprising:
a negotiator that negotiates a codec used for communication between the communication terminal apparatus and a counterpart terminal at a start of the communication, using an IP multimedia subsystem (IMS) signaling including one of a session description protocol (SDP) offer and an SDP answer, the negotiated codec being a codec that supports bandwidths of input signals of a plurality of codecs, and that changes a bandwidth of an input signal during the communication with the counterpart terminal by changing a frequency range of the input signal; and a bandwidth determiner that limits the bandwidth of the input signal of the codec during the communication with the counterpart terminal, according to signaling for limiting the bandwidth of the input signal of the codec, the signaling being notified from a network node.