The routing of a call or message that is placed for a disconnected or nonexistent telephone number or terminal address to an operator position or to an especially designated terminal 把對網(wǎng)絡(luò)中未連接的或不存在的電話號碼(或終端地址)所進(jìn)行的呼叫(或報文)轉(zhuǎn)交給操作員(或?qū)iT指定的終端)的路由選擇方法。