AT&T MERLIN LEGEND Release 3.1 System Manager's Manual page 82

Control Unit
Modules Supporting Extensions
Table 3 1 describes the type of equipment that each module supports. This
section highlights some important points about extension modules.
NOTE:
Extension jacks connect to individual telephones and to adjuncts that are
attached to extensions. Some adjuncts and applications serve the whole system
and connect directly to line/trunk jacks.
Extension Jacks
While the jacks that support MLX extensions and the jacks that support analog
extensions may look the same, there is a major difference: an MLX extension
jack actually supports two extension numbers at each location served by the
jack.
When you use an adapter called a Multi-Function Module in an MLX telephone,
you can connect a T/R device (for example, a modem, a fax machine, or an
answering machine) to that telephone. Even though a single extension jack on
the module serves both the phone and T/R device, each device has its own
extension number and operates independently. In contrast, if you want to use
both an analog multiline telephone and a modem or other adjunct at the same
location in the system and give each one its own extension number, you must
use two physical extension jacks on the module.
The Voice Announce to Busy feature, which allows a telephone user to hear a
voice page (also called a voice-announced call ) while on another call, has the
same requirements as an adjunct that operates independently from the phone:
one extension jack (and no adjunct) for an MLX phone; two extension jacks for
an analog multiline telephone. Single-line telephones and cordless or wireless
telephones (which are analog multiline telephones) cannot receive voice pages.
NOTE:
There is a distinction between an extension jack (sometimes referred to as a
logical ID or port ) and an extension number . In system programming, you
sometimes need to use port/jack/logical ID numbers rather than extension
numbers or system line/trunk numbers. Port/jack/logical IDs are numbered,
starting at 1, from the bottom of a module, and are fixed: they cannot be
changed. The extension and line/trunk numbers that people in the system dial
are flexible and can be programmed.
3–8
System Components