Customizing Your Phone472. Select Enabled from the pull-down list of Dual-Headset.3. Click Confirm to accept the change.NoteTwo types of DSS keys: Line Keys and Programmable Keys. Details will be introduced inthe following. The SIP-T42G IP phone supports 15 line keys.You can assign predefined functionalities to line keys. You can also define a label for theline key feature which will appear on the LCD screen. Line keys allow you to quicklyaccess features such as call return and voice mail. The line key LEDs will indicate themonitored status when line keys are assigned with particular features, such as BLF. Thedefault key type of line key 1-3 is Line. The default key type of line key 4-15 is N/A, whichindicates that this line key provides no functionality until configuration.To assign functionality to the line key via phone user interface:1. Press Menu->Features->DSS Keys.2. Select the desired line key, and then press the Enter soft key.3. Select the desired key type from the Type field.Dual headset is configurable via web user interface only.