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.

• 把对网络中未连接的或不存在的电话号码（或终端地址）所进行的呼叫（或报文）转交给操作员（或专门指定的终端）的路由选择方法。