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Lesson 1 the pstn
The document provides an overview of topics to be covered in Lesson 1, including the Public Switch Telephone Network (PSTN), its role, and an example of how customer premises equipment (CPE), specifically telephones, work. It will discuss the PSTN's original design for voice services and how it has evolved to support modern data and video. It will also explain the major elements of the PSTN - CPE, access systems, transport networks, and signaling - using telephones as an example CPE to illustrate how one piece of equipment interfaces with the PSTN. The lesson objectives are to understand the PSTN and learn how telephones connect to and utilize the network.
In this document
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Introduction to PSTN, its role and structure with a focus on Customer Premises Equipment (CPE). Discusses types of CPE like telephones and how they integrate with PSTN. Details the major elements of PSTN including mesh networks, access systems, and the demarcation point separating customer equipment from provider infrastructure.
Explains residential and business access systems in PSTN, differentiating between analog and digital circuits and elaborating on termination equipment.
Examines the ongoing relevance of PSTN in delivering voice, data, and video services, highlighting its importance for VoIP, cellular calls, and private line networks.
Focus on CPE, detailing its types and functionality, specifically examining how telephones work and interact with PSTN, covering concepts like DC current and signaling.
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Lesson 1 the pstn
- 1. Lesson 1 Topics PSTNOverview The Role of The PSTN CPE – An Example, How A Telephone Works Lesson 1 Topics PSTN Overview The Role of The PSTN CPE – An Example, How A Telephone Works Public Switch Telephone NetworkPublic Switch Telephone Network Thought For The Week Building on Lessons Learned In TCM 134 TheThe
- 2. Study This SetOf PowerPoint Slides Complete Assignment 1 And Post All Answers In The Lesson 1 Drop Box By The Due Date.
- 3. In This Lesson,You Will Learn How The Public Switch Telephone Network (PSTN) Was Originally Designed To Carry Voice Services. Next, We Will Learn That The Original Design Of The PSTN Has Evolved To Carry Most Of Today’s Advanced Voice, Data And Video Services. You Will Study A Brief Overview Of The PSTN – A Building Block For Our Course. Finally, You Will Learn How One Piece Of CPE Works In Conjunction With The PSTN. Objectives
- 4. Section 1.1 –PSTN Overview
- 5. The Public SwitchTelephone Network (PSTN) Is A Mesh Network Of Lines, Trunks, Switches, Etc. That Connects Customer Provided Equipment (CPE) Together To Allow The CPE To Communicate Together. The PSTN Was Originally Designed To Optimize The Transmission Of Voice Services. What Is The PSTN?
- 6. Major Elements OfThe PSTN CO Class 5 Switch CO Class 2 Switch Residence CPE CO Class 1 Switch PBX or KTS Digital LoopAnalog Loop Digital Interoffice Trunks Office Bldg PSTN
- 7. There Are FourMajor Elements Of Today’s Public Switched Telephone Network (PSTN). Customer Premises Equipment (CPE) Access System Transport Signaling The Four Major Elements Of The PSTN
- 8. Prior To 1984And The Breakup Of The AT&T Monopoly, All Parts Of The Public Switched Telephone Network Was Owned And Operated By The Telephone Company. After 1984, The Ownership And Maintenance Of All Telecommunications Equipment And Wiring On The Customer’s Site Became The Responsibility Of The Customer. Customer Premises Equipment
- 9. Customer Premises EquipmentIncludes:Customer Premises Equipment Includes: Telephones Fax Machines Wiring & Jacks Multiplexers Cross Connect Systems Computers PBXs Key Systems CSUs DSUs Video Codecs Etc.
- 10. Customer Premises Equipment- Continued:Customer Premises Equipment - Continued: Each Of These Pieces Of CPE Are Different. They Each Work Differently Electronically, And Many Have Different Ways In Which They Connect To The PSTN. Later In This Lesson We Will Study In More Detail, As One CPE Example, How Telephones Work Electronically And How They Connect To The PSTN. Later In This Course, We Will Study How Several Other CPEs Work Electronically And How They Connect To The PSTN.
- 11. The FCC DefinedA Point, The Demarcation Point, In The Telecommunications Network That Separates CPE From Telephone Company-Provided Equipment And Wiring. The Demarcation Point Is Often Referred To As The Demarc. Demarcation Point
- 12. The Access ComponentOf The PSTN Provides Customers All Of The Wiring And Equipment For The Customer’s CPE To Be Connected To The Central Core Of The Public Switched Telephone Network. The Access System Includes Both Lines And Trunks And The Termination Equipment In The End Office. Access Lines And Trunks Along With The Telephone Poles, Conduits, Connector Boxes, Etc. Are Referred To As The Local Loop. Access System
- 13. Some Samples OfEnd Office Termination Equipment. Central Office Termination Equipment
- 14. Most Access CircuitsRun From The Carrier’s Central Office And A Residence Are Analog Circuits (Ref. Slide 6). Most Access Circuits Run Between The Carrier’s Central Central Office And Businesses With Private Branch Exchanges Are Digital Circuits (Ref. Slide 6). Since Most Circuits That Connect Central Offices To Customer Premises Are Connected To Residences, Then, Most Circuits In The Local Loop Are Analog. Access System
- 15. Access System –Residential Access Class 5 Switch Each Customer Circuit Is A Two-Wire Cable From The Customer Demarc Out To The First Cross Connection Box A & B – Cross Connection Pedestal Or Cross Connection Box
- 16. Access System –Residential Access Class 5 Switch Even Though Customer Circuits Are Two-Wire Cable, Carriers Will Install Either 2-Pair, Or 4-Pair Cable. Customer Circuits Are Combined With Other Circuits At The Cross Connection Box 2-Pair Cable 100-Pair Cable
- 17. Access System –Residential Access Class 5 Switch Each Customer Circuit Is A Two-Wire Cable From The Customer Demarc Out To The First Cross Connection Box. From The Cross Connection Box To The Central Office The Customer Two-Wire Circuit Is Carried Inside Of A Much Thicker Cable That Carries 100 Pairs Of Cable Or More. Each Customer’s Two-Wire Circuits Remain Separate From Other Customer’s Circuits Which Are Carried On Separate Sets Of Wires.
- 18. Plastic Insulator Metal Conductor Sample4-Pair Cable The Photo Below Shows A 4-Pair Copper Wire Cable Similar To The Type Of Cable That Might Be Run To A Residence. Each Pair Of Cable Supports A Separate Circuit. Because Of The Cost Of Installing Outside Cable, Carriers Usually Install More Than 1 Pair Of Wires.
- 19. Access System –Business Access Class 5 Switch Access For Small Business Customer Circuits Are Similar To Residential Access Circuits. Business Trunks From PBXs Are Digital, Usually T1s Or T3s. If The Trunks Are T1s, 24 Separate End-User Applications Are Carried On One Set Of Wires At A Time. We’ll Study More About Data Rates Of Trunks In The Lessons In Module 3 Of Our Text. Trunks Business W/ PBX
- 20. Transport Component OfThe PSTN Transport Means Transmission – Taking Voice, Data, And Video Signals From One Subscriber’s Access Line And Delivering Them To Another Customer’s Access Line. The End-Office, Or Class 5 Central Office Is The Point Where All Customer Access Lines Connect. The Trunks Within The Transport Core Include A Wide Variety Of Transmission Speeds (e.g. T1, T3, OC-1, OC-12) And Transmission Media (e.g. Copper And Optical Fiber). We’ll Study More About The Transport System Later In This Course.
- 21. Signaling Component OfThe PSTN Signaling Means The Controlling Of Calling Including: Setting Up A Path For A Conversation Through The Transport Core. Maintaining And Terminating The Conversation Path. Collecting Billing Information. Handling Other Supervisory Functions. We’ll Study More About The Signaling System Later In This Course.
- 22. Section 1.2 –The Role Of The PSTN
- 23. Many People ViewVoice Services, And The PSTN Used To Deliver Those Services, As “Old, Ho- Hum” Topics. Those People Reason That The Most Lucrative, Future Growth Areas In Telecommunications Will Be In Data Services As Opposed To Voice Services. Many Of Those People Believe That Telecommunications Students Should Not Study Topics Related To Voice Communications Services And The PSTN. The Role Of The PSTN
- 24. Those Same PeopleBelieve That Data Communications Will Underpin The New Emerging Technologies And Will Be The “Wave Of The Future”. Why Then Study Plain Old Telephony? The Role Of The PSTN - Continued
- 25. Throughout This CourseWe Will Learn How POTS And The PSTN Play Vital Roles In Providing Many Services Such As: Voice-over-IP (VoIP) Third Generation Cellular Internet Applications E-Mail E-Commerce WANs & MANs Etc., Etc., Etc. Today’s Emerging Technologies Do These Services Seem Like POTS!
- 26. Cellular – ManyMajor Cellular Features Depend On The PSTN – Two Examples Follow Several Examples Of The Role Of The PSTN
- 27. A Cell CallPlaced To A Land-Based Phone Travels Through The PSTN CO Class 5 Switch CO Class 2 Switch CO Class 1 Switch Analog Loop Digital Interoffice Trunks Radio Controller MTSO Cellular User Residence CPE
- 28. InternetSS7/ PSTN Cellular Roaming DependsOn The PSTN SS7 Network Roaming MTSO Home MTSO VLR HLR SSP SSP STP STP Roaming Cellular User Cellular Roaming Would Not Be Possible Without SS7 Network In PSTN
- 29. Private Line DataNetworks Rely On Several Elements Of The PSTN Another Example Of The Role Of The PSTN
- 30. Site A Site B 56Kbps Private Line Site E 56 Kbps Private Line T3 Private Line Site D OC3 Private Line Site C 56 Kbps Private LineT1 Private Line PSTN Backbone Circuits Are Provisioned To Create Corporate Private-Line Data Networks Router Router Router Router Router
- 31. Internet Access ReliesOn The PSTN – Another Example
- 32. ISP Access UsePSTN Circuits CO Class 5 Switch CO Class 2 Switch CO Class 1 Switch Multiplexed/Channelized Digital Loop Analog Loop Digital Interoffice Trunks Residential End-User ISP MCDL Corporate End-User PSTN Router
- 33. Section 1.3 –Customer Premises Equipment
- 34. CPE Includes AllTelecommunications-Related Equipment That Is Located On The Consumer’s Side of the Demarcation Point. Customer Premises Equipment Customer Premises EquipmentCustomer Premises Equipment
- 35. Let’s Study HowTelephones, One Type OfLet’s Study How Telephones, One Type Of CPE, WorksCPE, Works Example Of Some Modern Telephones
- 36. Direct Current (DC) -An Electrical Charge Flows Steadily In One Direction Over the Conductor. Voltage Over Time In A DC Circuit Time Voltage + - Do You Remember From TCM 134 How DC Current Flows?
- 37. DC Voltage Resistor R I DC Voltage Resistor R IFlows When Switch Closed DC Series Circuits With & W/O A Switch Ohm’s Law: V = I x R
- 38. DC Voltage Resistor R Do YouRemember From TCM 134 How A Capacitor Affects Current Flow In A Circuit? Does I Flow? Does Current Flow In Circuits A Or B? Capacitor AC Voltage Resistor RCapacitor Does I Flow? Ohm’s Law: V = I x R
- 39. A View OfA Telephone Set
- 40. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # Examine The Diagram Below To See If You Can Apply Any Of The Lessons Learned From The Previous Two Slides. Under What Conditions Will Current Flow (1) Through The Ringer, (2) Through The Keypad, and (3) Into The Hybrid Coil. Closed Functional Diagram – Telephone Set
- 41. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # What Should The CO Switch Do First? What Should The CO Switch Do Next? Closed What Does The Central Office Do To Allow You To Dial Your Telephone?
- 42. A Touch TonePhone Operates By Transmitting A Combination Of Two Frequencies Each Time A Button Is Pressed. Pressing Each Button Sends Out A Different Combination Of Frequencies. How Does DTMF Dialing Work?
- 43. Rotary Dialing -A User Chooses A Number And Turns A Wheel From That Number To The Finger Stop Then Releases The Wheel. Finger Stop How Does Rotary Dialing Work?
- 44. The Phone’s InternalElectronics Repeatedly Breaks The Electric Current To Signal The Number Dialed. The Interrupts In The Current Causes Pulses Of Specific Lengths, These Pulses Of Interrupted Current Flow Are Used In Pulse Dialing Rather Than Frequencies To Represent Each Digit. How Does Rotary Dialing Work? - Continued
- 45. To Dial TheNumber “2” The Phone’s Electronics Breaks The Current 2 Times. To Dial The Number “9” The Phone’s Electronics Breaks The Current 9 Times. Question: How Is The Number “0” Dialed? How Does Rotary Dialing Work? - Continued
- 46. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # How Is Current Transitioned From The Two-Wire CO Circuit To The Four Wires Required To Operate The Receiver And Transmitter? What Is An Impedance Mismatch & How Does It Apply Here? Closed Operation Of The Receiver And Transmitter
- 47. Carbon Filled Receiver/Transmitter CarbonParticles Used To Create Current. Transmitter - The Input Voice Alternately Compresses The Carbon Particles Which Create A Matching Oscillating Current. Receiver – The AC Current From The Telephone Wires Moves A Membrane Which In Turn Alternately Compresses The Carbon Particles Which Produces Sound.
- 48. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # What Is The Role Of The Hybrid Coil Or Hybrid Network? What Is The Role Of The Balancing Network? Closed Hybrid Coil And The Balancing Network
- 49. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # What Should The CO Switch Do First? What Should The CO Switch Do Next? Open How Does The Central Office Ring Your Telephone?
- 50. RingerLine From CO R T Switch Hook Hybrid Coil Balancing Network Receiver Transmitter 1 23 4 5 6 7 8 9 * 0 # When The Switch Hook Is Closed, Current Flows. Closed Current Current Functional Diagram – Telephone Set: Switch Hook Closed
- 51. The Electronics WithinEach CPE Listed Earlier Works Differently. All CPE Are Similar, However, Since They All Eventually Create Electrical Signals Which Are Transmitted Over Telecommunications Wiring And Those Signals Are Received By A Compatible Piece Of CPE. Later In This Course, We Will Have The Opportunity To Study How Additional CPE Works. Summary Of CPE