| 摘要 |
PURPOSE:To improve the using efficiency between different exchanges by handling a pair of channels of an ADPCM signal capable of 23kbps as a channel capable of 64kbps in units and transmitting a trunk line through an exchange. CONSTITUTION:When telephone terminals 3 and 6 call simultaneously telephone terminals 29 and 37, a pair of ADPCM signal (32kbps) from the terminals 3 and 6 are buried on a channel of 64kbps in units in an exchange terminal device 11 in terms of a channel converter circuit 12, and transmitted to an exchange 17 through an exchange 15 and trunk line 16. Then a pair of signals of 32kbps are reproduced through a bit inserting circuit 18 and bit deleting circuit 20, and PCM signals of 64kbps can be obtained through a pair of ADPCM/PCM signal converters 19 and 21. These PCM signals are transmitted to exchange terminal devices 22 and 30 and further transmitted to the terminals 29 and 37. |
