T23: Key Telephone Systems

Overview

Telecommunications managers must understand that as with all forms of telecommunications technology, key systems are evolving.  New products enter the market regularly and the older models are adopting new features.  It is interesting to see that key telephone systems have gone through so many upgrades that they offer features that used to be exclusive to PBX (Private Branch Exchange).  Therefore, it is becoming more and more difficult to distinguish features that are offered by PBX vs. key system.  This summary will provide information about the various key systems and gives recommendation to help telecommunication managers in purchasing key system.

Comparing The Systems

In today’s world any experienced information technology manager will suggest that the best way of bringing a communication systems with adequate capacity and less cost is to compare the features and capacity of various systems, while keeping future growth in mind.  Evaluating a telecommunication service should follow the same guidelines.  When a telecommunication manager is called upon to evaluate the current system or plan for a feature system, he or she needs to consider the following:

Features Of The Key System

Since the focus of our discussion is in the Key system we will assume that after evaluating the above systems the telecommunications manager of a small organization decides to purchase a key system.  The next step for the telecommunications manager is to find out which features are essential for an affective organizational support in order to select the key systems sophistication level.  Most key systems including KSU-less have in common the following features:
·        Call Pickup
·        Call Hold
·        Supervisory Signals
·        Common Bell

Most electronic systems have the following additional features:
·        Automatic Hold Recall
·        Conferencing
·        Data Port Adaptor
·        Direct Station Selection
·        Do Not Disturb
·        Hands –free Answer Back
·        Intercom
·        Last Number Redial
·        Message Waiting
·        Music on Hold
·        Power Failure Transfer
·        Privacy
·        Remote Maintenance
·        Speed Dial
·        Station Display
·        Station Restriction
·        Voice Call

In addition to these features, many systems have feature that were one exclusive to PBXs:
·        Call Forwarding
·        Call Park
·        Direct Inward Dialing
·        Automatic Route Selection
·        Station Message Detail Recording
·        T1/E1 Compatibility
·        Uniform Call Distribution
·        Voice Mail

Purchasing Criteria

Finally, once the features are determined the telecommunications manager should evaluate other criteria such as:
·        Capacity: Key telephone systems should be purchased with a view towards long-term future
·        Open Architecture: An open architecture interface is important for future computer-telephony applications.
·        Cost: The failure rate and the cost of repairing failure should be considered part of the cost
·        Voice Mail: Voice mail is one of the most desired features among the users purchasing new key systems
·        Centrex Compatibility: Many features require Centrex compatibility such as call transfer, which requires a second dial tone
·        Number of Intercom Paths: Provides links throughout the network without blocking the switching
·        ISDN Computability: ISDN may become an important factor in near future
·        Power-failure Conditions: Battery backup needs to be included
·        Wired vs. Programmable Logic: Wired is simple with more failure, programmable logic offers more features
·        Station Equipment Interface: Making sure that the current stations interface with the key system or the appropriate new stations are purchased
·        Attendant Intercom Feature: Attendant can announce calls over the intercom
·        Station Features: Speed-dial and list of speed dial numbers