| 摘要 |
PURPOSE:To attain in-system calling with excellent operability and high quality by using a channel loss fixing means to fix the loss of each call signal level variable means to a prescribed value when an in-system call channel is formed. CONSTITUTION:When a talker depresses an in-system call button of a stationary equipment in a standby state, a control circuit 65 selects changeover switches 21, 31 respectively from the position of a wired line 1 to the position of an internal line 61. Moreover, an OFF control signal is fed to switches 63, 64. Thus, even when each of signal level variable circuits 24, 29, 34, 41 is set the automatic operating state, the control signal is interrupted by the switches 63, 64, resulting that a prescribed preset loss is set fixedly to each of the signal level variable circuits 24, 29, 34, 41. Thus, in-system call with high quality is implemented by proper sound volume. |
