Using Cisco CallManager
At the heart of any telecommunications system is a device responsible for performing
call management: the Private Branch Exchange (PBX).The PBX system is
nothing more than hardware with an operating system that recognizes when
someone starts to place a call, determines what number the person is dialing, and
then determines what piece of hardware in the PBX system it will use to route the
call to the destination. If the call is local, the PBX operating system understands
that the destination is local, and does not route the call to outside resources.
This determination is based upon what is known as the dial plan, and the
Cisco CallManager is the software component of the VoIP system that makes that
determination. In another designation, CallManager is sometimes knows as an IP
PBX system.The dial plan is merely the configuration of the CallManager such
that the site’s area code and prefix is used to help CallManager determine if the
destination call is local or outside of CallManager’s control.This section will discuss
CallManager, its features, and how it works to control calling behavior.