User Guide SIP-T22P IP Phone40To enable Dual Headset via web user interface:1. Click on Phone->Features->Audio Settings>>.2. Select Enabled from the pull-down list of Dual Headset.3. Click Confirm to accept the change.There are two types of DSS keys: Line Keys and Programmable Keys. The details will beintroduced as following. The SIP-T22P IP phone supports 3 line keys.You can assign predefined functionalities to the line keys to use quick access featuressuch as call return and voice mail. The line keys LED will indicate the monitoring statuswhen the keys are assigned specific features, such as BLF. The default key type of eachline key is Line.To configure 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.4. (Optional.) Select the desired key event from the Key Type field.5. (Optional.) Select the desired line from the Account ID field.6. (Optional.) Enter the corresponding value in the Value field.7. (Optional.) Enter the corresponding value in the Extension field.8. Press the Save soft key to accept the change or the Back soft key to cancel.You can also configure the line key via web user interface at the path Phone->DSSKeys->Line Keys.The line key features are explained in the following subchapters in detail: Speed Dial Voice Mail Direct Pickup Group Pickup DTMF Prefix Local Group XML Group XML Brower