| 摘要 |
PROBLEM TO BE SOLVED: To automatically switch a CATV line to a general line (NTT) when the CATV line is unavailable for performing bidirectional communications via a center between a plurality of communication terminals connected to the CATV line. SOLUTION: In the communication device for the bidirectional line, a general telephone line 28 is connected to a communication terminal in addition to a CATV line 5 so as to use the CATV line 5 preferentially rather than the general telephone line 28 in any case except the case that a call incoming communication terminal is busy or that a speech channel is busy. When the call incoming communication terminal is busy or when the speech channel is busy, the call incoming side communication terminal is automatically switched from the CATV line 5 to the general telephone line 28. COPYRIGHT: (C)2004,JPO&NCIPI
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