| 摘要 |
PROBLEM TO BE SOLVED: To provide a key telephone system which can follow frequent changes of unavailable service numbers of an IP telephone service provider without storing the unavailable service numbers thereof, thus making update of such stored numbers unnecessary. SOLUTION: A key telephone master system 10, accommodating lines of the IP telephone service provider and NTT lines, has a function F32 of preferentially hunting a line of the IP telephone service provider at the time of originating an outgoing call. In the above key telephone master system 10, when the outgoing call is originated through the line of the above IP telephone service provider, and when a busy tone is detected instead of a successful connection to a called party, there are provided a means F38 for releasing the line of the IP telephone service provider, and a means F39 for hunting the NTT line, thereby automatically re-originating a call to the above called party. COPYRIGHT: (C)2005,JPO&NCIPI
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