1. Telephony Networking

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 labeled A 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 Mbps

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

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

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"

51. Troubleshooting Tools (cont'd)
Tone and probe kit
A tone generator emits tones across a wire
A probe listens on the other end of the wire for tones emitted by the tone generator
Uses
Identify open circuits
Locate short circuits
Identify breaks in a cable
Test polarity of a line
Determine line voltage
Identify lines that are causing crosstalk
Find a single conducting wire in a bundle of wires
Provide talk battery power to test a line with no dial tone

52. Troubleshooting Tools (cont'd)
Multimeter
Measures resistance, current and voltage in an electrical circuit

53. Troubleshooting Tools (cont'd)
Punchdown tool
Inserts wires in 66 and 110 punchdown blocks
Line tester
Determines if a short exists in a line
Laptop computer
Connects to a telephony network and uses packet sniffers to troubleshoot lines
Additional devices
ABS
DTMF decoder
Acoustic coupler
Modular breakout adapter

54. Troubleshooting Analog Lines
PBX and ground-start analog lines
At the PBX, use a butt set to isolate crosstalk to determine if the problem is within or outside the building
Securing connections with a punchdown tool
Poorly closed connections or improperly set lines can cause line noise
Checking for line noise
Use a digital multimeter to measure for AC voltage
AC voltage > 1 volt = improper grounding

55. Troubleshooting Digital Lines
Improper clocking configuration
Voice and data lines must be precisely synchronized using the CO's PRS
Use a butt set to check for improper clocking
Check the Service Profile Identifier (SPID)
No connection will occur if the SPID is missing or incorrect
SPID = area code + 7-digit phone number + ISDN number
Check for proper termination
Be aware of different ISDN voice-encoding standards

56. Troubleshooting Digital Lines (cont'd)
Consider signal-to-noise ratio
Test equipment for digital networks
Signal/spectrum analyzer
Multimeter
Oscilloscope
Network analyzers
Time domain reflectometer (TDR)
Service-specific test set

57. Telephony Power Issues
Grounding/earthing
When connecting telephony and LAN-based equipment, ensure that all systems have only one ground path
Use an earth loop tester to avoid grounding problems
Ensure that power is connected properly at the electrical termination device (circuit breaker)
Physical security
Place all equipment in a dedicated server or CTI room
Telephones and ring voltage
REN value determines the ringing voltage
-90 v AC charge needed to ring a standard analog telephone

58. Summary 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

59. Lesson 5: Analog and Digital Signaling

60. Objectives Describe signaling categories and audible progress tones
Compare and contrast in-band and out-of-band signaling
Describe analog signaling in regard to E&M, loop-start and ground-start trunks
Describe digital signaling, including T1 and ISDN lines
Describe the nature and functions of Private Integrated Services Networks (PISNs)
Discuss Signaling System Seven (SS7)
Describe Computer-Telephone Integration

61. Signaling Categories Signaling categories:
Supervision – detects changes to a particular line
Addressing – responsible for routing signals to the correct switch
Alerting – audible alert signals
Call progress – signals that maintain calls
Audible call progress tones:
Dial tone
Busy signal
Receiver off hook too long
Nonexistent number

62. In-Band and Out-of-Band Signaling
In-band signaling
The process of allowing the control signal to share the same path as the voice and data
Out-of-band signaling
The process of using a separate channel for signaling purposes

63. Analog Signaling Ear and mouth (E&M) signaling
Separate signaling wires for voice and data

64. Analog Signaling (cont'd)
Grounding on E&M lines
Immediate start
Wink start
Delay-dial start
Reducing E&M trunk glare with wink starting

65. Loop-Start Analog Trunk Signaling

66. Ground-Start Analog Trunk Signaling (Idle and Outgoing Calls)

67. Ground-Start Analog Trunk Signaling (Incoming Calls)

68. Digital Signaling T1 lines and in-band signaling
Channelized T1 – 24 channels of 56 Kbps for voice and data
Unchannelized T1 – Mbps for voice and data
Bit robbing
The practice of using the least significant portions, or bits, of a data or voice channel for signaling
The T1 Superframe (SF) robs the A and B bits for signaling
The Extended Superframe (ESF) has four bits (A, B, C and D), though only A and B are used

69. Digital E&M Signaling
A and B bit settings for sending and receiving switches:
Idle – A and B bits are set to 0 for both switches
Call initiation – switch A sets bits A and B to 1; switch B sets bits A and B to 0
Call completion – both switches have the A and B bits set to 1

70. Digital Ground and Loop Starts
When an FXS is idle:
The CO's A and B bits = 1
The PBX's A bit = 0; the B bit = 1
When a digital loop-start line is in an idle state:
The A bits for the CO/FXO and PBX/FXS = 0
The B bits for the CO/FXO and PBX/FXS = 1
When an FXS or PBX makes an outgoing call:
The CO/FXO's A bit = 0; the B bit = 1
The PBX/FXS's A bit = 1; the B bit = 1

71. Integrated Services Digital Network (ISDN)
ISDN can carry voice, FAX, imaging or data communications
Two types of ISDN:
ISDN Basic Rate Interface (BRI) – Two 64-Kbps channels for voice or data; one 16-Kbps channel for signaling
ISDN Primary Rate Interface (PRI) – Kbps channels for voice or data; one 16-Kbps channel for signaling
B channel (bearer channel) – carries voice or data
D channel (delta channel) – carries signaling
H channel – combined B channels

72. ISDN Protocols
I.430 – explains how the ISDN interface uses the physical and data link layers of the OSI/RM (Layers 1 and 2, respectively)
ISDN interfaces must use reference points between the telco and the end station:
U interface
S interface
T interface
Network Termination Equipment (NTE)
Terminal adapter
Terminal equipment

73. ISDN Protocols (cont'd)
High Level Data Link Control – Link Access Protocol D Channel (HDLC – LAPD)
Used in ISDN connections to provide signaling
LAPD operates solely in the D channel of an ISDN line
LAPD provides flow control and data reliability
Q.931 and Q.932
Q.931 manages how a session is begun and ended
Q.932 makes it possible to modify connections that are already under way

74. Private Integrated Services Network (PISN)
PISN, showing connections via two different PINX types

75. Private Integrated Services Network (PISN) (cont'd)
A PISN consists of the following:
End nodes – provide specific services, including voice and data
Transit (transport) nodes – provide routing services to ensure that calls and network requests arrive at the proper destination

76. PISN Signaling Methods
Digital Private Network Signaling Scheme (DPNSS) – a collection of protocols that enable PBX-to-PBX communication over ISDN lines
Tromboning – a problem that occurs when a second connection is opened unnecessarily to accommodate a call that is being re-transferred back from one PINX to another
QSIG – the de facto standard for PISNs connected by PINX equipment through ISDN lines
QSIG basic services – enable PISN elements to establish voice and data calls
QSIG supplementary services – help control remote PINXs built by different manufacturers
Additional network features (ANF) – signaling enhancements that help handle calls

77. PISN Signaling Methods (cont'd)
QSIG basic call (QSIG BC)

78. Q and C Reference Points
Q reference point – the point at which a logical PINX interface communicates with a remote PINX
C reference point – the physical interface between a PINX and a trunk line

79. Signaling System Seven (SS7)
Signaling System Seven (SS7) – a packet-switched network protocol used by telcos in calls that pass between switches
High Level Data Link Control (HDLC) – a protocol that divides signaling data into discrete packets
HDLC allows three categories of stations (entities) to communicate:
Primary – initiates and controls communication
Secondary – responds to communication
Combined – controls and responds to communication
HDLC frame

80. Signaling System Seven (SS7) (cont'd)
SS7 elements:
Service Switching Point (SSP)
Signaling Transfer Point (STP)
Service Control Point (SCP)
SS7 message types:
Initial Address Message (IAM)
Address Complete Message (ACM)
Answer Message (AM or ANM)
Release Message (REL)
Release Complete (RLC)

81. Computer-Telephone Integration (CTI)
CTI – the ability for telephony networks and data networks to share data

82. Summary Describe signaling categories and audible progress tones
Compare and contrast in-band and out-of-band signaling
Describe analog signaling in regard to E&M, loop-start and ground-start trunks
Describe digital signaling, including T1 and ISDN lines
Describe the nature and functions of Private Integrated Services Networks (PISNs)
Discuss Signaling System Seven (SS7)
Describe Computer-Telephone Integration

83. Telephony Networking Telephony Essentials Investigating the Local Loop
Infrastructure Issues and Standards
Troubleshooting
Analog and Digital Signaling