AT&T MERLIN LEGEND System Reference Manual page 403

Features
Feature Interactions
Allowed Lists
Auto Answer All
Auto Answer Intercom
Auto Dial
2-354 System Access
When a call is received at a specific System Access button on the principal
station, it rings on the principal station's System Access button as well as on
all Shared System Access buttons programmed for that specific button.
In the Hybrid/PBX mode, Shared System Access buttons cannot be assigned
to a single-line telephone, and multiline telephones cannot be assigned
Shared System Access buttons with a single-line telephone as the principal
station unless the single-line telephone is connected to an MFM.
An Intercom or System Access Voice button is not factory-set and cannot be
assigned via centralized telephone programming to a single-line telephone
or other tip/ring device connected to a 012 or 008 OPT module.
In the Hybrid/PBX mode, calls received on direct inward dialing (DID) trunks
ring on a System Access button and on all Shared System Access buttons
for the receiving button that are programmed to ring.
In the Hybrid/PBX mode, a user with an outward-restricted telephone cannot dial
an outside number on a System Access button (including Shared System
Access buttons) unless the number is on an Allowed List assigned to the
telephone being used. A user with a toll-restricted telephone cannot dial a toll
number on a System Access button (including Shared System Access buttons)
unless the number is on an Allowed List assigned to the telephone being used.
When Auto Answer All is activated, all calls received at an Intercom or System
Access Ring, or at an Intercom or System Access Voice button can be
answered automatically by the device connected to the GPA. If Shared System
Access buttons are assigned, they should be programmed for either Delayed
Ring or No Ring and the corresponding System Access button at the principal
station should be programmed for Immediate Ring. This prevents calls to the
principal station from being answered at the principal station and at stations with
the Shared System Access button.
Voice-announced calls received at the analog multiline telephone are not
answered by a device connected via a GPA since a ringing current is not sent to
the device.
When the Auto Answer Intercom feature is activated, the user can answer inside
calls by using the Hands Free Unit (HFU). This excludes calls received on a
Shared System Access button.
When an inside Auto Dial button is pressed, the system automatically selects an
Intercom or System Access button and turns on the speakerphone. When an
outside Auto Dial button is pressed, the system automatically selects an outside
line button in the Key mode, a Prime Line button in the Behind Switch mode, or a
System Access button in the Hybrid/PBX mode.