| 摘要 |
PROBLEM TO BE SOLVED: To obtain an internet telephone system, where it is not required for 2 channels of a called party's B channel to be in a non-communication state at the start of an internet telephone call and no charging is imposed on the called party in the case that the internet telephone call cannot be completed. SOLUTION: This internet telephone system has a caller side internet telephone set and a called party side internet telephone set. Both the caller side internet telephone set and the called party side internet telephone set have respectively an analog telephone interface section 11, a tone and pulse dial detection section 12 that converts an analog telephone number signal into a digital telephone number signal, a central processing unit 13 that discriminates whether the internet telephone call is available and controls the telephone set as a whole, an internet telephone available telephone number storage section 14 that stores telephone numbers available for the internet telephone call, and an ISDN interface section 15 that transmits/receives a message for setup or the like to/from an ISDN 3.
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