AT&T MERLIN LEGEND Release 4.0 Feature Reference page 98

Feature Reference
When a call is waiting in queue for an extension, no new calls are sent to the
extension until after the queued call is completed.
When the queue contains 64 calls (system limit), additional calls sent to the
queue result in a busy signal.
No more than 40 dialed digits can be included in a queued call.
In order to use Callback with pools consisting of loop-start trunks, the loop-start
trunks must be programmed for reliable disconnect.
Mode Differences
Hybrid/PBX Mode
Callback can be used for busy extensions and for outside calls on pools where
all trunks are busy.
Key and Behind Switch Modes
Callback can be used only for busy extensions. Line Request is used for busy
outside lines that are assigned to line buttons.
Telephone Differences
Queued Call Consoles
A QCC operator cannot use Callback.
Other Multiline Telephones
On all other multiline telephones, Selective Callback is activated by pressing a
programmed Callback button or by pressing the Feature button and dialing
On MLX display telephones, Selective Callback is also activated by pressing
the Feature button and selecting the feature from the display. If the user is on
another call when the system tries to call back, he or she hears an abbreviated
ring.
A multiline telephone user can queue more than one call to the same extension.
On a multiline telephone, cancel a callback request by pressing the SA or ICOM
button used to make the call, lifting the handset, pressing the Drop button, and
pressing the SA or ICOM button again. The red and green LEDs next to the
button go off, and the request is canceled.
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Callback
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