Avaya Nortel Communication Server 1000 Manual page 60

60 Features
Minimum requirements
The ACF feature for IP Phones has the following minimum requirements:
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ACF mode
The ACF feature for IP Phones enables an IP Phone to re-register in the
ACF mode during a supported system failure.
The ACF mode preserves the following:
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All other elements (the self-labeled line/programmable feature keys,
context-sensitive soft keys, and text areas) are retained until the user
presses a key or the connection with the Call Server is resumed. If the user
presses a key during the failover, the display is cleared and a localized
"Server Unreachable" message is displayed.
The IP Phone uses this new mode of re-registration only when the Call
Server explicitly tells the IP Phone to do so. IP Phones clear all call
information if they register to a Call Server or LTPS that does not support
the ACF feature.
IP Phone ACF timer
It is possible that there may be an LTPS supporting the ACF feature and an
LTPS that does not support the feature in the same system.
A situation can exist where it takes a long time to fix a failure and no failover
Call Server is available. During this time, if the user released the call by
pressing the Release key or hanging up the telephone, the call-associated
resources are not used. The call-associated resources still exist on the
Call Server because they are not released. To prevent this, the 10-minute
Call Server ACF timer is introduced for each call. The timer prevents call
processing-related resources from being unnecessarily used when an IP
Phone that had an active call unregisters and never re-registers.
The timer is set if:
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Copyright © 2003–2008, Nortel Networks
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Call Server must be running CS 1000 Release 4.5, or later software.
IP Phones (including IP Softphone 2050) must support Unistim version
2.9. (Use the isetShow command to determine the Unistim version.
One of the columns in the isetShow output is UNIStimVsn.)
active media session
LED states of the Mute, Handsfree, and Headset keys
DRAM content
the ACF call status is UNREGISTERED; that is, when both parties go
offline.
only one of the parties is offline, and the other party does not support
disconnect supervision.
Nortel Communication Server 1000
IP Line Fundamentals
NN43100-500 02.02 Standard
Release 5.5 4 February 2008