AT&T MERLIN LEGEND Release 4.0 Feature Reference page 48

Feature Reference
Other Multiline Telephones
Auto Answer Intercom cannot be used on MLX telephones, cordless
telephones, or wireless telephones.
Single-Line Telephones
The Auto Answer Intercom feature cannot be used on single-line telephones.
This includes single-line telephones with speakerphones.
Some single-line telephones (such as the 8110) have their own telephone based
Auto Answer feature, which can be used with a Release 4.0 or later MERLIN
LEGEND Communications System.
Considerations and Constraints
Auto Answer All should be used instead of Auto Answer Intercom to allow an
answering device to answer intercom calls. Auto Answer Intercom can cause
intercom calls to be dropped.
When Auto Answer Intercom is activated in Hybrid/PBX mode and a call is
received on an SA button, the HFU turns on, even if the button is programmed
for Delay Ring or No Ring.
Feature Interactions
Auto Answer All
Coverage
System Access/
Intercom Buttons
48
Auto Answer Intercom
Both Auto Answer All and Auto Answer Intercom can be programmed
on the same telephone, but they cannot be used at the same time.
Auto Answer Intercom does not allow a receiver with an analog multiline
telephone to use an HFU to answer calls received on a Primary Cover,
Secondary Cover, or Group Cover button.
When Auto Answer Intercom is activated, the Hands-Free Unit (HFU)
answers inside calls received on an SA button. The HFU does not
answer calls on a Shared SA button.