AT&T MERLIN LEGEND Release 4.0 Feature Reference page 360

Feature Reference
When the ALS sequence is set to select an SA or ICOM button, an
outside line can be selected by dialing the Idle Line Access code
(usually
dial-out or Automatic Route Selection code in Hybrid/PBX mode. If ALS is
set to select an outside line button before an SA or ICOM button, the
device cannot be used to make inside calls (inside calls can be received
only).
Ring Timing options should be set to No Ring for each outside line on
which calls will not be received.
When the device is used only on personal lines for supplementary
answering (such as an answering machine) or ringing (such as an
external alert) and trunks are assigned to or removed from the associated
MLX telephone, the trunks should also be assigned to or removed from
the MFM.
When the device is used for both inside and outside calls to supplement
ringing (external alert) or to answer or screen calls (answering machine),
calls can be redirected to the device by assigning a Primary Cover,
Secondary Cover, Group Cover, or Shared SA button. In addition, the
MLX telephone user can activate Forward and Follow Me to redirect
incoming calls to the device. However, Coverage and Forward and
Follow Me should not be used simultaneously.
NOTE:
Forward and Follow Me (including Remote Call Forward) and Privacy are not
recommended because the user does not have an LED that indicates when the
feature is active.
Considerations and Constraints
When both the MLX telephone and the device connected to an MFM are in use,
the Voice Announce to Busy feature cannot be used to reach the MLX telephone
user. Voice Announce to Busy interferes with data calls made to a data station
including an MFM.
The tip/ring or SAA interface is selected by setting pin straps in the MFM. Only
authorized technicians can install or set options in the MFM.
When Ringing/Idle Line Preference is turned on for an MFM and Automatic Line
Selection is set to an outside trunk, inside calls cannot be made and features
cannot be used. Both inside and outside calls can be received.
Calls are independently sent to the MLX telephone and its associated MFM. The
following features can be used when the user wants calls to be received at both
the MLX telephone and the device connected to an MFM:
Cover buttons
Shared SA buttons
360
Multi-Function Module
) in Key and Behind Switch modes, or by dialing the pool