Telephony Networking

1. TelephonyNetworking

2. Lesson 1:Telephony Essentials

3. Objectives • Describe the basic components of the telephone service • Describe industry standards and protocols • Identify the purpose and function of the central office • Identify ways to connect to the central office • Identify various types of trunks and signaling methods • Explain various digital signal hierarchy terms and issues • Discuss SONET and SDH • Describe the purpose of the primary reference source • Describe the functions and uses of various types of telephone cable and wiring plans • List the common call-processing steps

4. Telephony Basics • Basic telephone service consists of: • Public switched telephone network (PSTN) – a system of interconnected lines and switches • Plain old telephone service (POTS) – standard telephony wires that carry analog data • The last mile – the POTS portion of the PSTN that connects to a home or business (usually 2.5 miles) • The local loop – the tip and ring wire in the RJ-11 connector that provide a complete circuit to the central office • On-hook condition – the line is not busy and is ready for a connection • Off-hook condition – the line is busy

5. Telephony Basics (cont'd) • Phone company terminology: • Local exchange carrier (LEC) – the local telecommunications company • Local access and transport area (LATA) – the area serviced by a LEC • Incumbent local exchange carrier (ILEC) – a telco already in business before the Telecommunications Act of 1996 • Competitive local exchange carrier (CLEC) – a company that competes with LECs and ILECs • Interexchange carrier (IXC) – a company that carries long-distance calls between LECs in different LATAs

6. Industry Standards and Protocols • International Telecommunications Union (ITU) – manages worldwide telephony and networking standards • ITU-T series – standards documents labeledA through Z • Radio Equipment and Telecommunications Terminal Equipment directive – determines standards for wireless devices in the United Kingdom and Europe • Internet Engineering Task Force (IETF) – publishes Requests for Comments (RFCs) that provide information about standardized Internet protocols

7. The Central Office • Central office (CO) – switching location for local and long-distance calls • CO uses three types of switches: • Class 3 (also known as an IXC, remote or long-distance switch) • Class 4 (also known as a tandem switch) • Class 5 (also known as an end-office switch) • Pulse Code Modulation (PCM) – converts analog voice data to digital format, then back to analog • PCM uses two compression algorithms: • Mu-Law (used only in North America and Japan) • A-Law (the standard for all international circuits)

8. CO Connections • Point of presence (POP) – an interexchange carrier that connects long-distance services to a local connection • Foreign Exchange Service (FX) – provides telephone services from a CO that is outside the local calling area • Private Branch Exchange (PBX) – enables an organization to create in internal telephone-numbering system • Centrex – enables an organization to provide a pool of lines (alternative to PBX) • Direct Inward Dialing (DID)/Direct Dialing Inward (DDI) – enables multiple telephone numbers to be used on a few lines

9. Trunks and Signaling • Trunk – a direct communication line between two switching systems; used to establish end-to-end communications between customers • Ear and mouth (E&M) trunks – carry voice and data on one series of lines, and signaling on a separate set of lines • Analog loop-start trunks – use two wires (the tip and the ring) to act as conductors for the connection • Ground-start trunk lines – require that both ends of a connection detect ground before the tip and ring wires can create a loop • Digital trunk lines – signaling information and data are sent digitally • A and B bits – signaling bits that allow a line to determine when connected systems check for dial tone and whether a remote system is in an on-hook or off-hook condition

10. Digital Trunks and the Digital Signal Hierarchy • Digital signal hierarchy (DSH) – provides a standard for digital signal levels • Use DSH to purchase the required amount of network bandwidth to accommodate telephone and network connections • DSH levels are analogous to the T-carrier system • Digital signals use frames to carry data and addressing information: • Super frame • Extended super frame (the most common standard)

11. SONET and SDH • Synchronous Optical Network (SONET) • High-speed, fiber optic networks organized in rings • Synchronous Digital Hierarchy (SDH) • Fiber ring networks used internationally • Essentially the same as SONET

12. SONET and SDH (cont'd) The basic measure of SONET speed is the Synchronous Transport Signal level 1 (STS-1) frame, which travels at 51.84 Mbps

13. SONET and SDH (cont'd) The basic unit for SDH is the Synchronous Transport Module (STM)-1 frame, which travels at 155.52 Mbps

14. SONET and SDH (cont'd) Benefits of using SONET/SDH • You can use multiplexors and routers to combine different data lines and streams onto one line • One heterogeneous network can communicate with another distant heterogeneous network via one fiber optic ring

15. The Primary Reference Source • Primary reference source (PRS) – a network of hyper-accurate clocks used to precisely time digital connections • PRS strata • Stratum 1 – extremely accurate but very expensive • Stratum 2 – used by long-distance providers • Stratum 3 – used by the CO • Stratum 4 – used by PBXs • Timing types • Asynchronous – no timing information is shared • Synchronous – a common system clock is used for all trunk lines and networks involved • Plesiosynchronous – a number of PRS clocks are used for all networks involved

16. Cabling and Wiring • Service wire center – houses one or more local switching systems • Main distribution frame (MDF) – the main interface between the telco's lines and all internal lines • Patch panel – interconnects voice and data lines with RJ-11 and/or RJ-45 connectors • Intermediate distribution frame (IDF) – connects the MDF and a user's telephone handset • Combined distribution frame (CDF) – same as MDF and IDF but also houses connections from incoming lines and lines from inside equipment • Minimum point of entry (MPOE) – the point at which phone lines first enter your facility • Network interface device (NID) – terminates the connections from the central office • Load coil – device that improves voice transmission • Bridge tap – cable used to extend the loop

17. Call-Processing Steps • Placing a call • Call setup – the connection is built between the local loop and the CO • Call connection maintenance – the connection is established and maintained • Call completion – breaking the connection • Common analog transmission impairments • Loss – parts of the transmission are dropped • Echo – parts of the conversation are repeated • Noise – unwanted energy that interferes with the signal • Crosstalk – parts of another conversation are heard • Echo cancellation in hybrid networks • When two-wire and four-wire networks are connected, a hybrid network is created, which can result in echo • An echo canceller balances the ohm levels between the lines, thereby eliminating the echo

18. Summary • Describe the basic components of the telephone service • Describe industry standards and protocols • Identify the purpose and function of the central office • Identify ways to connect to the central office • Identify various types of trunks and signaling methods • Explain various digital signal hierarchy terms and issues • Discuss SONET and SDH • Describe the purpose of the primary reference source • Describe the functions and uses of various types of telephone cable and wiring plans • List the common call-processing steps

19. Lesson 2:Investigating the Local Loop

20. Objectives • Explain the importance of a demarcation point in telephony • Identify signaling types used in the local loop • Use numbering standards, including the North American Numbering Plan (NANP) and United Kingdom standards • Explain how the local loop is wired • Wire RJ-11 and RJ-12 connectors • Wire BT-431A and BT-631A connectors • Wire a wall jack and a line jack unit

21. Inside the Demarcation Point • Minimum point of entry (MPOE) • The telco's demarcation point • The point where telco equipment ends and inside local loop wiring begins • Drop wire – the line from the telephone pole to the MPOE • Station wire – the line inside the MPOE

22. Getting to the Local Loop • Global numbering plans • ITU Recommendation E.164 establishes standards for numbering plans • Telephone numbers should not exceed 15 characters • North American Numbering Plan (NANP) • Numbers are 10 digits long

23. Getting to the Local Loop (cont'd) • Area code jeopardy and relief • Realignment – move areas from one area code to another • Split – create a new area code • Three-way split – create two new area codes out of one area code • Overlay – assign a new area code in the same geographic area as an existing area code • Specified Numbering Scheme (SNS) • Enables people in the U.K. to make calls using a uniform formula

24. Signaling Types • Three types of signaling: • Rotary/pulse or multi-frequency (MF) – used on rotary dial phones • Dual tone multi-frequency (DTMF) – generated by touch-tone pads on all standard phones • Digital – does not process audible tones

25. RJ-11 Connectors and Wiring

26. RJ-11 Connectors and Wiring (cont'd) • Telephone jacks constitute a tip and ring • Tip • The "transmit" wire • The positive side of the circuit (in relation to the ring) • Ring • The "receiving" wire • The negative side of the circuit (in relation to the tip)

27. RJ-12 Modular Connector

28. RJ-11 Wall Connector Wiring

29. BT-431A Connectors

30. BT-631A Connectors

31. Line Jack Units • Three types of line jack units • Master • PBX master • Secondary • Master line jack units contain: • A 26-amp surge protector • A 1.8 uf, 250-volt capacitor • A 470-ohm service resistor • Six terminals designed to accept wiring from the wall

32. Wall Jack Wiring Diagram

33. Summary • Explain the importance of a demarcation point in telephony • Identify signaling types used in the local loop • Use numbering standards, including the North American Numbering Plan (NANP) and United Kingdom standards • Explain how the local loop is wired • Wire RJ-11 and RJ-12 connectors • Wire BT-431A and BT-631A connectors • Wire a wall jack and a line jack unit

34. Lesson 3:Infrastructure Issues and Standards

35. Objectives • List common telephony connectivity and safety issues • Identify safety procedures • Explain safety standards • Determine the proper cabling procedures for specific environments • Identify various cable terminations • Wire an RJ-45 connector • Explain the importance of plenum cabling • Explain the necessity of securing equipment

36. Common Telephony Issues • Quality assurance and business continuity • Uptime – the length of time a device has remained operational • Mean time between failure (MTBF) – the predicted amount of time a device will function before it requires maintenance or replacement • Return on investment (ROI) – the calculations made to ensure that equipment will result in company profitability • Telecommunications reliability and safety issues: • Extreme temperatures • Vibration and shock • Humidity • Fire • Noise • Altitude

37. Common Telephony Issues (cont'd) • Electromagnetic compatibility • Electrostatic discharge (ESD) – An uncontrolled buildup of electrical current • Radio frequency interference (RFI) – A signal that causes another device to operate improperly • Electromagnetic interference (EMI) – interference produced by electromechanical devices • Solutions for electrical issues: • EMI suppression filters • Capacitors • Inductors • Line filters • Shielding • Ensuring proper humidity • Personnel safety concerns and procedures

38. Network Equipment Building System • Network Equipment Building System (NEBS) • Protects people and property • Ensures operational continuity in the telephony industry • NEBS sets standards for the operation of telephony equipment with respect to: • Earthquake zones • Operating conditions and transport conditions • Levels of contaminants • NEBS standards documents • GR-63-CORE (Physical Protection) • GR-1089-CORE (Electromagnetic Compatibility and Electrical Safety)

39. Standards Bodies Standards bodies provide telephony standards • Independent Committee for the Supervision of Standards of Telephone Information Services (ICSTIS) • International Organization for Standardization (ISO) • Independent Testing Laboratory (ITL) • European Telecommunications Standards Institute (ETSI) • Federal Communications Commission (FCC) • Telecommunications Industry Association (TIA) • Electronic Industries Alliance (EIA) • British Standards Institute (BSI)

40. Proper Cabling Procedures When pulling cable: • Avoid sharp bends in the cable • Take care to eliminate sharp edges in conduits and other areas where cable might get worn or cut • Make sure that wiring does not interfere with mechanical equipment • Avoid passing wire close to fluorescent lights • Ensure that you are using the right type of cable for a particular job

41. Choosing the Proper Cable • American Wire Gauge (AWG) standard • Standard gauges • 22 AWG – floor or wall cable • 24 AWG – backbone and drop cable • 26 AWG – drop cable and devices that pass data between similar devices (daisy chaining) • The EIA/TIA 568 standard is the most commonly used for twisted pair cabling

42. RJ-45 connector – an eight-pin modular cable ending used in Ethernet networks Crossover cabling – allows two systems to communicate without the use of an intermediary device, such as an Ethernet hub IBM Cabling Standard

43. Serial Cable Termination • Data terminating equipment (DTE) – a serial device that transmits and receives data digitally • Data communications equipment (DCE) – a device that is attached to a communications line and is capable of altering a signal in transit • RS-232 – a standard that enables DTE and DCE devices to communicate • Universal Asynchronous Receiver-Transmitter (UART) – translates parallel communication into serial • Additional ITU communication standards • V.24 through V.90

44. PVC vs. Plenum Cabling • Plenum – the space above a dropped ceiling or behind a wall • UTP or STP cables have a polyvinyl chloride (PVC) jacket (emits toxic gas when burned) • When installing cable in a plenum: • Encase UTP or STP cable in a protective metal conduit • Use plenum cabling (has a Teflon jacket that inhibits burning)

45. Securing Equipment • Physically secure telephony equipment using brackets • Isolate power sources by grounding them properly • PBX grounding: a steel rod 6 feet (2 meters) underground to which you attach the PBX ground lead

46. Summary • List common telephony connectivity and safety issues • Identify safety procedures • Explain safety standards • Determine the proper cabling procedures for specific environments • Identify various cable terminations • Wire an RJ-45 connector • Explain the importance of plenum cabling • Explain the necessity of securing equipment

47. Lesson 4:Troubleshooting

48. Objectives • Identify common troubleshooting tools • Use a line test handset (butt set) • Use a tone and probe kit • Use a digital multimeter • Use a line tester • Discuss how to troubleshoot analog lines • Discuss how to troubleshoot digital lines • Discuss telephony power issues

49. Short (continuity) Open (open fault) Terminator Cross Polarity Split Line imbalance Loopback testing End-to-end testing Troubleshooting Terms

50. Troubleshooting Tools • Telephone line test set • Also called a butt set or handset • Used to test line quality • Used to check line polarity • Used to determine loss of current • End-to-end and loopback testing • A butt set is used to generate tones and frequencies to test lines • Can use analog butt sets to listen to digital communications by going into "data safe mode"