Introduction to public switched telephone network pstn pdf
We begin with a history lesson, understanding how and why telephone networks and the companies that provide them are organized into local access and inter-city transmission, or as we will see, Local Exchange Carriers LECs and Inter-Exchange Carriers IXCs. Then we will establish a basic model for the PSTN and understand its main components: Customer Premise, Central Office, loop, trunk, outside plant, circuit switching, attenuation, loop length, remotes, and why knowledge of the characteristics of the loop remains essential knowledge even though we are moving to Voice over IP.
Next, we'll cover aspects of telephony and Plain Ordinary Telephone Service, including analog, the voiceband, twisted pair, supervision and signaling including DTMF. The course is completed with an overview of SS7, the control system for the telephone network in the US and Canada. On completion of this course, you will be able to draw a model of the Public Switched Telephone Network, identify and explain its components and technologies including:.
Most of this course is devoted to mobile wireless telecommunications. We begin with basic concepts and terminology including base stations and transceivers, mobile switches and backhaul, handoffs, cellular radio concepts and digital radio concepts. Then, we cover spectrum-sharing technologies and their variations in chronological order: CDMA for second generation, 1X vs.
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This course is completed with a lesson on WiFi, or more precisely, The remaining four courses in the CTNS package are on the "IP" telecommunications network and its three main enabling technologies: This course establishes a framework for all of the subsequent discussions: This framework is required to sort out the many functions that need to be performed, and to be able to discuss separate issues separately.
First, we'll define the term "protocol" and compare that to a standard. Then we'll define "layer" and how a layered architecture operates, and provide an overview of the name, purpose and function of each of the seven layers in the OSI model. Then, we'll go back through the story more slowly, with one lesson for each of the layers, examining in greater detail the functions that have to be performed and giving examples of protocols and how and where they are used to implement particular layers.
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The result is a protocol stack, one protocol on top of another on top of another to fulfill all of the required functions. To make this more understandable, this course ends with the famous FedEx Analogy illustrating the concepts using company-to-company communications, and an analogy of Babushka dolls to illustrate how the protocol headers are nested at the bits level. The IP packets and routing of the previous course is one part of the story. Performance guarantees, and methods for quality of service, traffic management, aggregation and integration is another big part of the story, particularly once we leave the lab and venture into the real world and the business of telecommunications services.
We'll begin by establishing a basic model for a customer obtaining service from a provider, defining Customer Edge, Provider Edge, access and core, and a Service Level Agreement: Next, we'll understand virtual circuits, a powerful tool used for traffic management and how they are implemented with MPLS, explaining the equipment, jargon and principles of operation. TCO Certification is proof of your knowledge of telecom, datacom and networking fundamentals, jargon, buzzwords, technologies and solutions.
Each course has a course exam, consisting of ten multiple-choice questions chosen at random from a pool and shuffled in order. Passing the course exams proves your knowledge of these topics and results in your certification as a Certified Telecommunications Network Specialist. You may also order a signed and sealed Certificate by airmail.
Alternatively, if you like this discounted package of courses, but don't need the certification — or don't feel like writing exams — no problem! Take the Telecom, Datacom and Networking for Non-Engineers course package , which includes the same courses as the CTNS certification package, without the certification exams. One benefit of TCO certification is differentiating yourself from the rest of the crowd when applying for a job or angling for a promotion. This type of knowledge and preparation makes you an ideal candidate to hire or promote to a task, as you will be able to build on your knowledge base to quickly get up to speed and work on a particular project - then have the versatility to work on subsequent projects.
TCO Certification will help demonstrate you have this skill Take advantage of these courses for individual learning, a team, or for an entire organization. The scalable myTeracom Learning Management System can register and manage all of your people through their courses, lessons and exams, and generate management reports showing progress and scores with the click of a button. For larger organizations, the courses and exams can also be licensed and deployed on an organization's internal LMS. Teracom certification packages are an extremely cost-effective way of implementing consistent, comprehensive telecommunications and networking technology fundamentals training, ensuring that both existing resources and new hires are up to the same speed, with a common vocabulary, framework and knowledge base.
The course exams provide concrete measurements of competency in key knowledge areas. Management can view the progress and results of all team members and export the results to Excel with the click of a button. These reports identify skills deficiencies and strengths, and provide tangible proof of return on investment and team readiness for reports to upper management.
What is the value of the CTNS certification? Click here to find out. Register for a Telecom Certification.
Register for Online Courses. Training Request Form. Courses Available for Private Onsite Seminars. Certifications Included with Seminars. TCO Certifications: Save with Bundles. Telecom Textbook Review. Teracom Training Institute. This free online telecom training course lesson is the introduction to the course.
Want to Keep Going? Get this course online: Join our thousands of satisfied customers including:. This will not disappear overnight, but will continue to be supported for decades into the 21st century. Even with Voice over IP telephony, at least the last foot will still be analog: Each telephone was wired to a telephone exchange established for a town or area. For communications outside this exchange area, trunks were installed between exchanges.
Networks were designed in a hierarchical manner until they spanned cities, countries, continents and oceans. Automation introduced pulse dialing between the telephone and the exchange, so that each subscriber could directly dial another subscriber connected to the same exchange, but long distance calling across multiple exchanges required manual switching by operators.
Later, more sophisticated address signaling, including multi-frequency signaling methods, enabled direct-dialed long distance calls by subscribers, culminating in the Signalling System 7 SS7 network that controlled calls between most exchanges by the end of the 20th century. The growth of the PSTN meant that teletraffic engineering techniques needed to be deployed to deliver quality of service QoS guarantees for the users. The work of A.
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Erlang established the mathematical foundations of methods required to determine the capacity requirements and configuration of equipment and the number of personnel required to deliver a specific level of service. In the s, the telecommunications industry began implementing packet-switched network data services using the X. In the s, the industry began planning for digital services assuming they would follow much the same pattern as voice services, and conceived end-to-end circuit-switched services, known as the Broadband Integrated Services Digital Network B-ISDN.
At the turn of the 21st century, the oldest parts of the telephone network still use analog technology for the last mile loop to the end user. Several large private telephone networks are not linked to the PSTN, usually for military purposes.
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- Course The PSTN Lesson 1: Introduction.
There are also private networks run by large companies which are linked to the PSTN only through limited gateways , such as a large private branch exchange PBX. The task of building the networks and selling services to customers fell to the network operators. In some countries, however, the job of providing telephone networks fell to government as the investment required was very large and the provision of telephone service was increasingly becoming an essential public utility.
For example, the General Post Office in the United Kingdom brought together a number of private companies to form a single nationalized company. In more recent decades, these state monopolies were broken up or sold off through privatization. In most countries, the central has a regulator dedicated to monitoring the provision of PSTN services in that country. Their tasks may be for example to ensure that end customers are not over-charged for services where monopolies may exist.
These regulatory agencies may also regulate the prices charged between the operators to carry each other's traffic. The PSTN network architecture had to evolve over the years to support increasing numbers of subscribers, calls, connections to other countries, direct dialing and so on. The model developed by the United States and Canada was adopted by other nations, with adaptations for local markets.
Public switched telephone network - Wikipedia
The original concept was that the telephone exchanges are arranged into hierarchies, so that if a call cannot be handled in a local cluster, it is passed to one higher up for onward routing. This reduced the number of connecting trunks required between operators over long distances and also kept local traffic separate. However, in modern networks the cost of transmission and equipment is lower and, although hierarchies still exist, they are much flatter, with perhaps only two layers.
Most automated telephone exchanges use digital switching rather than mechanical or analog switching. The trunks connecting the exchanges are also digital, called circuits or channels.
However analog two-wire circuits are still used to connect the last mile from the exchange to the telephone in the home also called the local loop. The call is then transmitted from one end to another via telephone exchanges. The call is switched using a call set up protocol usually ISUP between the telephone exchanges under an overall routing strategy.
The name given to this channel is Digital Signal 0 DS0. The DS0 circuit is the basic granularity of circuit switching in a telephone exchange. A DS0 is also known as a timeslot because DS0s are aggregated in time-division multiplexing TDM equipment to form higher capacity communication links. In modern networks, the multiplexing function is moved as close to the end user as possible, usually into cabinets at the roadside in residential areas, or into large business premises.
Public switched telephone network
These aggregated circuits are conveyed from the initial multiplexer to the exchange over a set of equipment collectively known as the access network. Within the access network, there are a number of reference points defined. Most of these are of interest mainly to ISDN but one — the V reference point — is of more general interest. This is the reference point between a primary multiplexer and an exchange.