AT&T MERLIN LEGEND Release 4.0 Feature Reference page 260

Feature Reference
System
Access/Intercom
Buttons
Transfer
Voice Announce
260
Forward and Follow Me
A Shared SA button cannot be used to turn on Forward or Remote Call
Forward for the principal's telephone. Calls received on a Shared SA
button are not forwarded.
When calls are forwarded to an extension, a call received on an SA or
ICOM button rings once at the forwarding extension's SA or ICOM
button (including all assigned Shared SA buttons, even though a call
received on these buttons is not forwarded) and rings at the destination
extension's SA or ICOM button (including all assigned Shared SA
buttons) until it is answered.
Inside and outside calls transferred by another user or by an operator
are forwarded. If a user transfers a call to an extension with calls
forwarded, the extension receiving the forwarded calls hears one burst
of ring, indicating an inside call. If the extension is a display telephone,
the call information appears as an inside call and not an outside call.
Returning transferred calls are not forwarded.
Voice-announced calls are not forwarded.