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Introduction to Packet Voice Technologies Cisco Networking Academy Program.

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Presentation on theme: "Introduction to Packet Voice Technologies Cisco Networking Academy Program."— Presentation transcript:

1 Introduction to Packet Voice Technologies Cisco Networking Academy Program

2 Traditional Telephony

3 Basic Components of a Telephony Network

4 Central Office Switches

5 What Is a PBX?

6 Basic Call Setup

7 Supervisory Signaling

8 Address Signaling –Tone telephone DTMF dialing Rotary telephone –Pulse dialing

9 Informational Signaling

10 Digital vs. Analog Connections

11 Time-Division Multiplexing

12 Frequency-Division Multiplexing

13 Packetized Telephony Networks

14 Packet Telephony vs. Circuit-Switched Telephony More efficient use of bandwidth and equipment Lower transmission costs Consolidated network expenses Increased revenue from new services Service innovation Access to new communications devices Flexible new pricing structures

15 Call Control

16 Distributed Call Control

17 Centralized Call Control

18 Packet Telephony Components

19 Real-Time vs. Best-Effort Traffic Real-time traffic needs guaranteed delay and timing. IP networks are best-effort with no guarantees of delivery, delay, or timing. Solution is quality of service end-to-end.

20 Foreign Exchange Station Interface

21 Foreign Exchange Office Interface

22 E&M Interface

23 T1 Interface

24 E1 Interface

25 BRI

26 Physical Connectivity Options

27 Cisco IP Phone

28 Analog Voice Basics

29 Local Loops

30 Types of Local-Loop Signaling Supervisory signaling Address signaling Informational Signaling

31 On Hook

32 Off Hook

33 Ringing

34 Ringing (Cont.)

35 Pulse Dialing

36 Dual Tone Multifrequency

37 Informational Signaling with Call-Progress Indicators

38 Trunks

39 Foreign Exchange Trunks Foreign Exchange Office –Connects directly to office equipment –Used to extend connections to another location Foreign Exchange Station –Connects directly to station equipment –Used to provision local service

40 Types of Trunk Signaling Loop start Ground start E&M Wink Start E&M immediate start E&M delay start

41 Loop-Start Signaling

42 Ground-Start Signaling

43 E&M Signaling Separate signaling leads for each direction E-lead (inbound direction) M-lead (outbound direction) Allows independent signaling

44 E&M Type I

45 E&M Type V

46 E&M Type II

47 E&M Type III

48 E&M Type IV

49 Trunk Supervisory Signaling— Wink Start

50 Trunk Supervisory Signaling— Immediate Start

51 Trunk Supervisory Signaling— Delay Start

52 2-Wire to 4-Wire Conversion and Echo Echo is due to a reflection. Impedance mismatch at the 2-wire to 4-wire hybrid is the most common reason for echo.

53 Echo Is Always Present Echo as a problem is a function of the echo delay and the loudness of the echo.

54 Echo Suppression

55 Echo Cancellation

56 Analog-to-Digital Voice Encoding

57 Digitizing Analog Signals 1.Sample the analog signal regularly. 2.Quantize the sample. 3.Encode the value into a binary expression. 4.Compress the samples to reduce bandwidth, optional step.

58 Basic Voice Encoding: Converting Digital to Analog 1.Decompress the samples, if compressed. 2.Decode the samples into voltage amplitudes, rebuilding the PAM signal. 3.Filter the signal to remove any noise.

59 Nyquist Theorem

60 Voice Compression Techniques Waveform algorithms –PCM –ADPCM Source algorithms –LDCELP –CS-ACELP

61 Example: Waveform Compression PCM –Waveform coding scheme ADPCM –Waveform coding scheme –Adaptive: automatic companding –Differential: encode changes between samples only ITU standards: –G.711 rate: 64 kbps = (2 * 4 kHz) * 8 bits/sample –G.726 rate: 32 kbps = (2 * 4 kHz) * 4 bits/sample –G.726 rate: 24 kbps = (2 * 4 kHz) * 3 bits/sample –G.726 rate: 16 kbps = (2 * 4 kHz) * 2 bits/sample

62 Compression Bandwidth Requirements

63 Mean Opinion Score

64 Perceptual Speech Quality Measurement

65 Signaling Systems

66 T1 Digital Signal Format

67 Robbed-Bit Signaling

68 Channel Associated Signaling— T1

69 E1 Framing and Signaling

70 Channel Associated Signaling— E1

71 Common Channel Signaling

72 ISDN –Part of network architecture –Definition for access to the network –Allows access to multiple services through a single access –Used for data, voice, or video Standards-based –ITU recommendations –Proprietary implementations

73 ISDN Network Architecture

74 Layer 3 (Q.930/931) Messages


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