AT&T MERLIN LEGEND Release 2.0 Equipment And Operations Manual page 44

Introduction
The following types of ICOM buttons can be used to make and receive inside
calls in Key mode:
An ICOM Ring button is used to make inside calls and to receive inside
and outside calls transferred from another extension. When an
ICOM Ring button is used to make an inside call, the telephone at the
destination extension rings once per ring cycle to indicate an inside call.
An ICOM Voice button is used to make inside calls and to receive inside
and outside calls transferred from another extension. When an
ICOM Voice button is used to make an inside call, the person at the
destination extension hears the caller's voice on the speakerphone after
a beep, rather than ringing. (If he or she has a single-line telephone,
does not have a speakerphone, or has disabled voice announcements,
the telephone rings the same as if the call had been made on an
ICOM Ring button.)
An ICOM Originate Only button is used only to make inside calls.
Neither inside nor outside calls are received on an ICOM Originate Only
button. This type of button ensures that the user always has a button
available to make or transfer a call, establish a conference call, answer a
Call Waiting call, or pickup parked calls. The button can be
programmed for either voice or ring operation.
A combination of up to 10 ICOM Voice, ICOM Ring, and ICOM Originate Only
buttons can be assigned to each telephone on buttons 1 through 10. The
number of personal line buttons that can be assigned to a telephone is limited
only by the number of trunks in the system and the number of buttons available
on the telephone. See System Planning for button diagrams.
System Configurations
Key
In Key mode, the system can be configured as a square, modified, or hybrid
Key system, as described in the following sections. (The communications
system does not distinguish among these configurations. )
In Key mode, the first eight trunks connected to the system are automatically
assigned to the same eight buttons on all multiline telephones; all trunks are
automatically assigned to each Direct-Line Console (DLC).
Square Key System
In a square Key system, every outside trunk in the system terminates on a
personal line button on every telephone in the system.
The system illustrated in Figure 1-3 is a square Key system in an office with
three outside trunks and three telephones. Each of the three trunks is assigned
to the same button on each telephone. When a trunk is assigned to a personal
line button on more than one telephone, it is considered a shared line.
1-16 Modes of Operation