National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC Private Branch Exchange At NIST, Berhampur Presented by Tapash BeheraEC Under the guidance of Mr. R. K. Dash

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC Introduction  The 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.

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC BASIC PRINCIPLES:

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC 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:

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC PBX Generations: Third Generation :  Fully digital switching and transmission.  Nonblocking-  architecture  Voice and data capability. Generation 3.5:  Fully. digital switching and transmission  Nonblocking  Provides ISDN standard interface (144 kbps 2B + D) desk to desk.  Compatible with CCITI No.7 common-channel signaling

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC PBX Generations: Fourth Generation:  Fully digital  Distributed architecture  LAN-based Fifth Generation:  Broadband digital switching and transmission via fiber optics.  Fully integrated voice, data, and full-motion video  Possibly integrated optical switching

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC FUNCTION OF A PBX  A 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

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC PBX ARCHITECTURES: BLOCKING AND NONBLOCKING  In digital PBX architectures, the terms blocking and nonblocking refer to the PBX's ability to handle data as well as voice.  the switching capacity of the PBX become "blocked" due to the amount of traffic traveling through it.  A nonblocking architecture is, therefore, one that guarantees that the switching capacity and operational control are such that heavy data call usage will not "block" the switch, causing either a partial or total loss of service.

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC DATA TRANSMISSION WITH A PBX  The 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.

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC 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 avail­able directly through the public network.  There are two types of subsections  Switched Services Networks (SSN)  Electronic Tandem Networks (ETN)

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC 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)

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC 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

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC 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.

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC Disadvantages  Limited 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.

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC CONCLUSION  The 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

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC Thank You!

National Institute of Science and Technology Technical Seminar Presentation Tapash Behera EC