PBX Systems for IP Telephony
Written by a recognized expert in telephony systems, this guide evaluates technologies, markets, and best practices for enterprise voice systems, messaging, and customer contact centers.
TABLE OF CONTENTS PBX Systems for IP Telephony
Chapter 5: Legacy PBX Traffic Engineering Analysis
The call processing system of a PBX is responsible for all control functions and operations. It is responsible for monitoring and supervising all system design elements, including the switching network, printed circuit boards, and peripheral equipment, including station terminals and trunk circuits. It is also responsible for basic call set-up and teardown, feature/function provisioning, and systems management and maintenance operations. The PBX system call processing design has evolved from a single processing element responsible for all control functions to many processing elements, each with very specific responsibilities and functions. The PBX call processing design may differ from system to system, but there is a similar set of functional elements and responsibilities that is common to all enterprise voice communications systems, regardless of system size or functional complexity. Figure 5-1 illustrates the main PBX processing elements in a typical configuration design.
Figure 5-1: Main PBX processing elements.
Common Control Complex
The PBX common control complex can best be described as the brain of the system. Although other systems and subsystems may be responsible for physical operations, such as switch connections and voice signal transport, the common control complex is the command center responsible for issuing orders and supervising operations. There are several main components in a typical PBX common control complex, including:
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Main System Processor
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Main System Memory
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System Control Interfaces
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I/O Interfaces
The common control complex can be a single printed circuit board containing all of the listed common control elements, or it can be...
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