1. Hands free style indoor phone with function of dual talking with outdoor station, intercom and remote unlocking. 2 wire system 2. Visitor image can be display on the screen. 3. Can supervise the front door situation at any time by pressing the monitor button. 4. Can adjust the contrast and brightness. 5. Intercom function is available. 6. SMPS and Adaptor are optional. 7. Hang mount type. 8. All kinds of the indoor phones and outdoor stations are totally compatible.