System Failover and Survivability
Transition from one SM to another SM/BSM is comprised of :
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- Limbo - The phone has lost its connection to its primary controller, but has not yet
detected this regardless of whether a user is on a call or not.
- Moving Subscriptions Interval (MSI) - The phone has detected a lost connection to the
primary controller and since it has already registered with a non-primary controller, this is
the brief interval between limbo and successful subscription to the non-primary controller.
The subscription can be moved regardless of whether a user is on a call or not.
- Call Preservation - During an active call, the phone has detected a lost connection to the
primary controller and exhibits media preservation behavior.
The Call Preservation Message Box or the Acquiring Services screen are not displayed
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during the Moving Subscription Interval (MSI).
MSI transition and failback to the primary SM occurs according to the failback behavior
described in
3. Select the active controller
Survivability configuration examples
Several survivability configurations are available, depending on your controller and system
management environment, as shown in the illustrations that follow.
Configuration Example 1
SIP software Release 6.0 and later offers simultaneous registration with multiple controllers,
and improved feature availability during and after failover to a secondary controller.
142 Deskphone SIP 9608, 9611G, 9621G, 9641G Administrator Guide Release 6.0.1
on page 147.