D-Link DPH-150S User Manual page 21

 Redial
 Release: Pressing the key, you can end the call.
 SMS
 Transfer
4. Set the type as Dtmf
You can configure the key as Dtmf. This key function allows you to easily dial or
edit dial number.
5. Set the type as URL
You need to match a XML Phonebook address, pressing the button you can
directly access the corresponding remote phonebook.
6. Set the type as BLF List Key
It needs the cooperation with the Broadsoft server. The traditional BLF is that
every number will need to be subscribed, so if the numbers that subscribed is so
many that it will cause to obstruction. However, BLF List Key will put the
numbers that needed to be subscribed in a group, and the phone use the URL of
the group to subscribe and analyze the specific information of each number such
as number, name, state and so on according to the notifications from the server.
Then set the idle Memory key as BLF List Key, later if the state of an object
changes, the corresponding LED will change.