Cisco OL-4660-01 - Manual (Page 4)

Chapter 4 Cisco Call Back
Introducing Cisco Call Back
4-4
Cisco CallManager Features and Services Guide
OL-4660-01
Call Back Handler
The Call Back Handler resides in the CEF service and receives the called
extension and calling extension information when the CallBack softkey is
pressed. Cisco CallManager passes this information to the CEF service through
the Cisco CTIManager interface.
The Cisco Extended Functions service determines the destination device by using
the Cisco CallManager Database Interface. The CEF service opens the line and
device by using Cisco CTIManager. When the called line becomes available, the
CEF service sends an audio alert (a twinkle sound) and visual notification on the
Cisco IP Phone through the Cisco CTIManager and XSI interfaces. Only one Call
Back can be active on a Cisco IP Phone. The Call Back Handler keeps this
information in memory. Phones and lines get opened through Cisco CTIManager
only for a Call Back-activated phone and called phone line. When the Call Back
notification goes to the Call Back-activated phone, the phone and lines that were
opened by Cisco CTIManager close.
Screen Saver and Call Back Dictionary
The screen saver of the Cisco Extended Functions service reads the XML
dictionary files and creates Document Object Model (DOM) objects for all
installed locales when the CEF service starts. The system uses these DOM objects
for constructing XSI screens that are needed by the Cisco IP Phone.
Redundancy Manager
When multiple Cisco Extended Functions are active within a Cisco CallManager
cluster, the redundancy manager uses an algorithm to determine which CEF is
active and which is the backup CEF. The Redundancy Manager uses the lowest IP
address of the server that is running the CEF service as the active service. The
remaining CEF services serve as backup services.
DB Change Notifier
The DB Change Notifier handles all the database change notifications, such as
service parameter changes, trace parameter changes, and alarm configuration
changes, and reports the changes to the CEF service.