| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that the convenience is poor because the change of setting is conventionally required for every call of a subscriber and an operation is complicated since it is necessary to register a encoding mode based on a use style of a transmission channel into a subscriber setting table. SOLUTION: A subscriber device controls selectors 24 and 25 at the time of line connection, and an ADPCM signal of 32 kbps is sent to a TDMA control circuit 27 at the time of transmission, and at the time of reception, the ADPCM signal of 32 kbps from a base station is converted into a PCM signal of 64 kbps by an ADPCM coder 23 to send to a subscriber circuit 11. A message sending circuit 26 generates and outputs an encoding mode change signal at the time of input of an output tone detecting signal of a tone detection circuit 20. A selector control circuit 22 controls the selector 24 and 25 so as to bypass the ADPCM coder 23 by the output tone detecting signal of the tone detection circuit 20.
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