| 摘要 |
PURPOSE:To prevent transmission delay and deterioration in sound quality as to every repeating exchange by interchanging a trunk line by concatenating the vocoder of each repeating exchange to the trunk line and by detecting the signal contents of an originating vocoder by the vocoder of each repeating exchange. CONSTITUTION:Vocoders 6-9 of respective repeating exchanges 2-5 are connected via trunk line 1 and when origination is made from exchange 2 to exchange 4 for a call, a dial signal transmitted from telephone set TEL1 of exchange 2 is supplied to vocoder 6 via exchange 10. This dial information is sent from vocoder 6 to trunk line 1 and then received at the same time by vocoders 7-9 of exchanges 3-5 to discriminate the incoming call. After the dial signal information received by vocoder 8 of exchange 4 which corresponds to the incoming call is discriminated by exchange 12, a connection between exchanges 2 and 4 is made and on the establishment of a call state, the call state is monitored by vocoders 7 and 9 of other exchanges 3 and 5 to prevent the deterioration in sound quality and transmission delay. |
