Lines Labeled For Modified Key System Telephones - AT&T MERLIN LEGEND System Reference Manual

Functional Description
FCC Registration
4-10 Modes of Operation
Modified Key System
A square Key system can be modified through system programming to provide
line access for special business needs. For example, because in many offices
not every user needs a tie trunk, the system is programmed so that not all
telephones have access to all lines.
The labeled line buttons for a modified Key system with two outside lines and
one tie trunk are shown in figure 4-3.
Figure 4-3 Lines Labeled for Modified Key System Telephones
Hybrid Key System
A hybrid key system is a composite of the Key and Hybrid/PBX modes of
operation. For the Key system, whether standard or modified, this allows
ground-start lines to be connected directly to the control unit.
To have ground-start lines in a hybrid Key system, the system must be
registered under an MF classification and the control unit must be modified to
allow programming of ground-start lines. Then the system can be programmed
for the Key mode. In the Key mode, all outside lines, including ground-start
lines, are assigned to line buttons on each telephone.
The AT&T account representative or authorized dealer who planned the
system's mode of operation provides the FCC registration number that the
customer reports to the local telephone company. In Key systems this number
includes the letters "KF" or "MF". The guidelines used to determine the system's
classification are as follows.