同义词
1)busy flash signal,占线信号2)engaged signal,占线信号3)busy signal,占线信号4)group busy signal,群占线信号5)engaged lamp,占线信号灯6)backward busying signal,反向占线信号7)backbusying signal,回程占线信号8)busy back,busy back signal,busy signal,占线信号;忙信号9)audible busy signal,音响占线信号10)busy lamp,占线信号灯，忙灯
