You have the system but no features? Add the feature package 1 to your existing Merlin 206 or 410 control unit and get conference call, speaker phone (requires BIS phone) as well as other features.
Features
Plug-in cartridge convenience
5 party conference call
On hook dialing, call transfer, hold reminder, group listening
Prevents outgoing calls on individual phones
Privacy
Automatic outside and intercom dialing
Last number redial, automatic line selection, do not disturb
