User Guide for the SIP-T41P IP Phone721. Press the OK soft key to activate auto redial.The LCD screen prompts the following:2. Wait for a period of time or press the OK soft key to redial the phone number.The phone will retry as many times as configured until the called party is idle.You can press a call return key to place a call back to the last incoming call.To configure a call return key via phone user interface:1. Press Menu->Features->DSS Keys.2. Select a desired DSS key.3. Press or , or the Switch soft key to select Key Event from the Type field.4. Press or , or the Switch soft key to select Call Return from the Key Type field.5. (Optional.) Enter a string that will appear on the LCD screen in the Label field.6. Press the Save soft key to accept the change or the Back soft key to cancel.Call return key is configurable via web user interface at the path DSSKey->Line Key.You can mute the microphone of the active audio device during an active call, and thenthe other party cannot hear you.To mute a call:1. Press during an active call.The mute key LED illuminates solid red.