AT&T MERLIN LEGEND Analog Direct-Line Console Operator's Manual page 16

Understanding Your Equipment
Additional call-handling information and features are available
on DLCs with displays. The Direct Station Selector (DSS) on
the MERLIN II System Display Console adds extension buttons
and other inside calling buttons. Use the extension buttons for
one-touch dialing to make or transfer calls to co-workers.
You can use a DLC with a headset, speakerphone, modem (a
device for sending computer data over phone lines), fax
machine, or answering machine. To use a fax machine,
modem, or answering machine, your phone must have special
equipment. See your system manager for more information.
Illustrations and descriptions of the DLCs and headset follow.
Procedures for using your DLC (with or without a headset) are
in Chapter 2, "Handling Calls," and Chapter 4, "Using Features."
Identifying Your Equipment 1 - 3