equipment engaged tone

An audible signal sent to a caller to indicate that a call cannot be completed, owing to congestion in some part of the network. In many systems busy tone is used for this purpose.; 由于网络某些部分发生了阻塞故障,送给呼叫者的一种音频信号,表示呼叫失败。在许多 系统中都使用忙音。