Cisco 7935 System Manual page 46

Chapter 40 Cisco IP Phones
Phone Administration Tips
The default specifies 10 phones per second. If a primary Cisco CallManager were
to fail, the phones will fail over to the secondary Cisco CallManager. The failover
process happens as fast as possible, using the priority queues to regulate the
number of devices that are currently registering.
When the primary Cisco CallManager recovers, the phones get returned to that
Cisco CallManager; however, you do not need to remove a phone from a working
Cisco CallManager, in this case the secondary, as fast as possible because the
phone is on a working system. The queue depth gets monitored (using the
MaxPhonesFallBackQueueDepth service parameter setting) to determine whether
the phone that is requesting registration gets registered now or later. If the queue
depth is greater than 10 (default), the phone stays where it is and tries later to
register to the primary Cisco CallManager.
In the Service Parameters Configuration window, you can modify the
MaxPhonesFallBackQueueDepth service parameter. If the performance value is
set too high (the maximum is 500), phone registrations could slow the
Cisco CallManager real-time response. If the value is set too low (the minimum
is 1), the total time for a large group of phones to return to the primary
Cisco CallManager will be long.
Dependency Records
If you need to find out what directory numbers a specific phone is using or what
phones a directory number is assigned to, click the Dependency Records link that
is provided on the Cisco CallManager Administration Phone Configuration or
Directory Number Configuration window. The Dependency Records Summary
window displays information about directory numbers that are using the phone.
To find out more information about the directory number, click the directory
number and the Dependency Records Details window displays. If the dependency
records are not enabled for the system, the dependency records summary window
displays a message.
For more information about Dependency Records, refer to "Accessing
Dependency Records" and "Removing a Directory Number from a Phone" in the
Cisco CallManager Administration Guide.
Cisco CallManager System Guide
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