AT&T MERLIN LEGEND System Reference Manual page 126

Features
Considerations
Feature Interactions
Account Code Entry
Transmission quality may vary during the conferencing of outside lines.
A call to a busy number cannot be added to a conference.
Pressing the Drop button and the line button for a participant also
disconnects a participant who joined the conference by using a shared
outside line or System Access button.
Conferences originated from multiline telephones can have a total of five
participants-the originator plus two outside lines and two extensions.
Conferences originated from single-line telephones can have a total of three
participants-the originator plus two others using any combination of inside
or outside lines.
If a single-line telephone with a timed disconnect is used (for example AT&T
models 2500YMGK-PEC 3178-NHL and 2500MMGK-PEC 3101-ETR),
pressing the switchhook automatically disconnects the call. With this type of
telephone, the Recall button must be used instead of the switchhook to add
a conference participant or drop the most recently added conference
participant.
When a conference originator puts the conference on Hold, Music-on-Hold is
not activated.
The system does not automatically select either an outside line or Intercom or
System Access button when the user presses the Conference button; the
user must select the line manually.
If the conference originator presses Conference, selects a line button, dials a
number, and presses Conference again before the person being called
answers, all conference participants hear ringback, which may cause voices
to cut in and out.
If the conference originator calls a co-worker and presses the Conference
button and the co-worker, while on hold for the conference, presses a Hold,
Conference, or Transfer button, the call is disconnected.
If a conference participant (excluding the originator) who is included on a
conference call on a System Access or intercom button leaves the
conference temporarily by putting the call on hold and then rejoins the
conference on a shared outside line or Shared System Access button, the
person is connected to the conference. However, the original conference call
appearance on the Intercom or System Access button is disconnected.
A separate account code must be entered for each outside call added to the
conference.
Conference 2-77