Nortel 2001 Installation And Operation Manual page 417

Appendix F: Active Call Failover
The Active Call Failover (ACF) feature enables an IP Phone to reregister in
the ACF mode during a Signaling Server failure.
The ACF mode preserves the following:
• active media stream
• LED status of the Mute, Handsfree, and Headset keys
• DRAM content
Note: All other elements (feature keys, soft keys and text areas) are
retained until the user presses a key or the connection with the Signaling
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 reregistration only when the Signaling
Server explicitly tells the IP Phone to do so. IP Phones clear all call
information if they register to a Signaling Server or Line Terminal Proxy
Server (LTPS) that does not support the ACF feature.
For more information on Active Call Failover, refer to IP Line: Description,
Installation, and Operation (553-3001-365).
IP Phones Description, Installation, and Operation
Page 417 of 430