() Direct Inward Dialing a system where an office building, a hotel, etc. can have a large range of telephone numbers sharing one or a small number of direct lines. Calls go directly to an extension without being connected by an operator or receptionist .直接拨入（一种办公电话系统，很多电话号码共有一个或几个直拨线路。电话可直接拨入分机而无需接线生或接待员连接）➡DDI