private branch exchange
TRANSCRIPT
University of Diyala College of EngineeringCommunication Department
Private Branch Exchange
Assistant lecturer
Ali Mohammed salh
Student Ibrahim abdul _
rhman M.
contents1. Introduction2. BASIC PRINCIPLES3. PBX Generations4. FUNCTION OF A PBX5. DATA TRANSMISSION WITH A PBX6. PBX NETWORKING7. Switched Services Networks8. Electronic Tandem Networks9. Advantages of using a PBX10.Disadvantages11.CONCLUSION
IntroductionThe PBX a device for switching telephone
calls within a building such as office , block or factory.
Before PBXs were computerized, the attendant manually connected both the caller and the person being called by physically inserting a cord.
PABX is simply an automatic version of the PBX. The PABX is also faster with data communication, and can handle more telephone calls at the same time.
PBX Generations
• First Generation:
Analog switching and transmission . Electronic Stored program control
• Second Generation: Analog transmission Some digital switching Blocking architecture providing limited data transmission capability
PBX Generations• Third Generation:
Fully digital switching and transmission .
Non blocking-
Voice and data capability.
• Fourth Generation:
Fully digital
Distributed architecture
LAN-based
PBX GenerationsFifth Generation:
Broadband digital switching and transmission via fiber optics .
Fully integrated voice, data, and full-motion video
Possibly integrated optical switching
FUNCTION OF A PBXA PBX is a means of providing switched communications
to a number of different users, usually within one or a group of buildings. The PBX also acts as the primary interface to either public or leased networks via either direct connection or a series of gateways
The present generation of PBXs are configured in a star topology, meaning that the PBX is a central switching unit to which all devices are directly attached
Transmission speed :
• Digital PBX : 64 Kbps , Non-standard system : higher data
• ISDN PBX : 144 Kbps rate
DATA TRANSMISSION WITH A PBXThe signal passes from the device connected
through the switch in a digitally encoded form, it matters little whether the originating device is a telephone, personal computer or a mainframe.
In the majority of third-generation PBXs the data transmission capability is provided by a modem that interconnects the terminal device with the PBX network .(modem pooling)
The high-bandwidth circuits in the office to support applications such as improved graphics, faster remote file access are used.
PBX NETWORKING
Networks can be managed and developed independently of the local PTT or network operator and can frequently offer a much higher degree of sophistication than would be avail able directly through the public network.
There are two types of subsections
Switched Services Networks (SSN)
Electronic Tandem Networks (ETN)
Switched Services Networks (SSN)
SSNs are communications packages designed by public carriers for large customer networks. To be classified as a SSN, a LEC switch, and private circuits provided by an IC must interconnect with multiple PBX systems.
There are three basic SSNs: Tandem Tie Trunk Networks (TTTN) Common Control Switching Arrangements
(CCSA) Enhanced Private Switched Communications
Services (EPSCS)
Electronic Tandem Networks (ETN)
Electronic Tandem Networks (ETN) consist of privately owned trunk and switching facilities. One important aspect of an ETN is a uniform numbering plan. Each switch has a specific location code
ETNs provide automatic routing of private network traffic and can take advantage of least-cost routing schemes. Additionally, ETN switches can define calling privileges for specific terminals or groups of terminals.
Most ETN switches can also support Satellite PBX systems. This is usually done through special switch trunks that make certain attendant and station features transparent to the network
Advantages of using a PBX
No rewiring necessary.Standard interfaces for attaching to the network.Not geographically limited.Provides gateway access to public and private data
networks.Any extension user can be equipped to transmit data
traffic.No difficulty in moves and changes.Main access point to ISDN.Good network management and network utilization
information.
DisadvantagesLimited transmission bandwidth. Designed primarily for voice traffic. PBX failure could be catastrophic if a large
proportion of all voice and data traffic are reliant on it.
High cost per port for voice and data, especially if only a limited number of data users.
PBXs are at present most widely used to switch voice, not data.
PBX is perceived as a telecommunications and not a data processing facility.
CONCLUSIONThe conclusion that can be derived from
the overall studies is that it is very simple in functioning. The PBX can act as main gateway to long distance networks for a variety of data communications
As this private branch exchange is experimental type, and dialing number is limited to a single digit, so some are to be made before put to actual use in large public places/buildings
