A button set to this function allows the user to see the caller ID of a call on another line without interrupting the current call to which they are connected.

If an extension already has a button set to this function, creating another button with this function will automatically clear the setting from the existing button.

This function is only supported on a button that includes LED/LCD indicator. The indicator is lit when the function is enabled.

To access this function without a programmable button:

On DS and ETR phones, press FEATURE and then dial 17.

On BST phones, press FEATURE and dial *0.