17-05-2013, 04:56 PM
Private Branch Exchanges (PABXs)
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Introduction
Business Telephone Switching Systems commonly called Private Branch Exchanges (PABXs) belong to the class of telecommunication equipment referred to as circuit switching systems. This class of systems allows sharing of the transmission resources of telephone networks. Their evolution encompasses manually controlled exchanges from the earliest times to stored-program controlled digital exchanges of the modern era. The use of stored-program control (SPC) systems in modern PBXs has led to the provision of a plethora of features in these exchanges that require proper understanding by business people in order to select PBXs providing the greatest benefit and competitive advantage at the lowest cost to their businesses.
These features are classified into system, attendant (operator), station, and management features. System features are PBX features that are programmed by the administrator or the assistant administrator using a proprietary telephone connected to a particular extension port designated for such a purpose or a console (usually a computer) connected to the console port of the PBX. Some PBXs allow remote programming of the PBX by the administrator. In all cases, the administrator or the assistant administrator is required to enter the correct password before changing the setting of a PBX feature. An attendant feature is programmable at the operator’s station using a proprietary telephone connected to certain extension ports designated for such. A station feature is one that can be programmed at any station or extension. The PBX administrator uses management features for system administration, control, and maintenance.
The programming of these features requires commands (specified in the PBX manual).
Objective of the Project
The objective of the project is to examine the voice telecommunication needs of business enterprises (Small and Medium-Scale Enterprises), on the one hand, and investigates the features of digital PBXs currently on sale in the Nigerian telecommunication markets, on the other hand, and comments on the usefulness of the functionalities of the above PBX features to the need of businesses.
Scope of the Project
The project is limited to the basic telephone services required of every modern business organization at the lowest level while at the highest level are unique aggregations of telephone services that satisfy the particular needs of an organization, e.g. hospitality, financial, retailing, etc.
Significance of the Project
The purpose of the project is to identify the telephone services provided by PBX to business organization especially small and medium scale enterprises (SMEs) and also be able to program some of the PBX features needed by the business organization
CHAPTER TWO
Private Branch Exchange
Private Branch Exchanges (PBXs) belong to the class of telecommunication equipment referred to as circuit switching systems. This class of systems allows sharing of the transmission resources of telephone networks. It is a telephone exchange that serves a particular business or office by making connections among internal telephones of a private organization-usually a business and also connects them to an external line.
Evolution of Private Branch Exchange
PBX development spans four generations [Pecar, et al, 1992]. First generation PBXs were manual electromechanical exchanges requiring human operators. Each operator sat in front of a vertical panel containing banks of ¼-inch tip-ring sleeve (3-conductor) jacks, each of which was the local termination of a subscriber’s telephone line. In front of the jack panel lay a horizontal panel containing two rows of patch cords, each pair connected to a cord. Second generation PBXs performed switching mechanically or electronically but used analog designs. The step-by-step electromechanical exchange and the stored-program controlled (SPC) electronic exchange developed in 1989 and the 1970s, respectively, belonged to this generation.
Telephone Services Required By Business Organizations
Every modern business organization requires certain telephone services. Some of these services have been identified elsewhere [Ghazali, et al, 2010]. At the lowest level are basic telephone services, which are used by all business organizations, while at the highest level are unique aggregations of telephone services that satisfy the particular needs of an organization, e.g. hospitality, financial, retailing, etc. These services can be further categorized as premises services and network services. Premises services, also called PBX services, are usually provided by equipment installed in an organization’s premises. Network services, on the other hand, are subscription services obtained from public networks operated by telecommunication service providers.
Basic PBX services required by business organizations include:
• Basic dial service: The most fundamental is station – to – station calling, using between three and five digits. Next is the ability to connect inside telephones (stations) with public and private external networks directly or through a telephone operator.
• Administration, Control, and Maintenance Services: These are required to produce reports such as Station Message Detail Recording (SMDR), which show calling and called numbers together with time, date and duration of calls; station/feature software moves, adds, and changes; maintenance support; voice messaging (also called voice mail); automatic call distribution (ACD), which directs large numbers of incoming calls to specific departments within an organization; message center/directory services; and cable/inventory/energy/property management.
Features of Modern PBXs
The PABX features described in this section were obtained from a study of the user’s manuals [PANASONIC, 2011and IKE, 2011] of two popular SPC digital PBX brands currently being sold in the telecommunications market at Alaba, Lagos. It should be pointed out that although the two PBX brands have certain common features, their feature counts are not the same. Also, it was observed that a number of the common features were described differently. While Panasonic brands are available only as wall-mounted PBXS, IKE PBXs are available as console, rack, and wall-mounted types. These differences are considered in this study to constitute likely sources of confusion to business people trying to make a choice among different brands.
Conclusion
The findings of a study of modern business exchanges (PBX) and their applications by Nigerian small and medium scale enterprises (SMEs) were presented. The study revealed that PBXs marketed in the Nigerian Telecommunication market are third-generation Stored Program Control (SPC) digital PBXs shipped with core PBX features. It was also found that SMEs especially hotels, insurance firms, stock brokerage firms, etc. depend on PBXs to provide premises voice (i.e. intercom) services.