1.Introccnamahdys.ppt

1
© 2005 Cisco Systems, Inc. All rights reserved. Cisco Public
IP Telephony
Introduction to Packet Voice
Technologies
Cisco Networking Academy Program

2
IP Telephony v1.0
Traditional Telephony

3
IP Telephony v1.0
Basic Components of a Telephony Network

4
IP Telephony v1.0
Central Office Switches

5
IP Telephony v1.0
What Is a PBX?

6
IP Telephony v1.0
Basic Call Setup

7
IP Telephony v1.0
Supervisory Signaling

8
IP Telephony v1.0
Address Signaling
Tone telephone
DTMF dialing
• Rotary telephone
– Pulse dialing

9
IP Telephony v1.0
Informational Signaling

10
IP Telephony v1.0
Digital vs. Analog Connections

11
IP Telephony v1.0
Time-Division Multiplexing

12
IP Telephony v1.0
Frequency-Division Multiplexing

13
IP Telephony v1.0
Packetized Telephony Networks

14
IP Telephony v1.0
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
IP Telephony v1.0
Call Control

16
IP Telephony v1.0
Distributed Call Control

17
IP Telephony v1.0
Centralized Call Control

18
IP Telephony v1.0
Packet Telephony Components

19
IP Telephony v1.0
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
IP Telephony v1.0
Foreign Exchange Station Interface

21
IP Telephony v1.0
Foreign Exchange Office Interface

22
IP Telephony v1.0
E&M Interface

23
IP Telephony v1.0
T1 Interface

24
IP Telephony v1.0
E1 Interface

25
IP Telephony v1.0
BRI

26
IP Telephony v1.0
Physical Connectivity Options

27
IP Telephony v1.0
Cisco IP Phone

28
IP Telephony v1.0
Analog Voice Basics

29
IP Telephony v1.0
Local Loops

30
IP Telephony v1.0
Types of Local-Loop Signaling
• Supervisory signaling
• Address signaling
• Informational Signaling

31
IP Telephony v1.0
On Hook

32
IP Telephony v1.0
Off Hook

33
IP Telephony v1.0
Ringing

34
IP Telephony v1.0
Ringing (Cont.)

35
IP Telephony v1.0
Pulse Dialing

36
IP Telephony v1.0
Dual Tone Multifrequency

37
IP Telephony v1.0
Informational Signaling with
Call-Progress Indicators

38
IP Telephony v1.0
Trunks

39
IP Telephony v1.0
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
IP Telephony v1.0
Types of Trunk Signaling
• Loop start
• Ground start
• E&M Wink Start
• E&M immediate start
• E&M delay start

41
IP Telephony v1.0
Loop-Start Signaling

42
IP Telephony v1.0
Ground-Start Signaling

43
IP Telephony v1.0
E&M Signaling
• Separate signaling
leads for each direction
• E-lead
(inbound direction)
• M-lead
(outbound direction)
• Allows independent
signaling

44
IP Telephony v1.0
E&M Type I

45
IP Telephony v1.0
E&M Type V

46
IP Telephony v1.0
E&M Type II

47
IP Telephony v1.0
E&M Type III

48
IP Telephony v1.0
E&M Type IV

49
IP Telephony v1.0
Trunk Supervisory Signaling—
Wink Start

50
IP Telephony v1.0
Immediate Start

51
IP Telephony v1.0
Delay Start

52
IP Telephony v1.0
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
IP Telephony v1.0
Echo Is Always Present
• Echo as a
problem is a
function of the
echo delay and
the loudness
of the echo.

54
IP Telephony v1.0
Echo Suppression

55
IP Telephony v1.0
Echo Cancellation

56
IP Telephony v1.0
Analog-to-Digital Voice Encoding

57
IP Telephony v1.0
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
IP Telephony v1.0
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
IP Telephony v1.0
Nyquist Theorem

60
IP Telephony v1.0
Voice Compression Techniques
• Waveform algorithms
PCM
ADPCM
• Source algorithms
LDCELP
CS-ACELP

61
IP Telephony v1.0
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

62
IP Telephony v1.0
Compression Bandwidth Requirements

64
IP Telephony v1.0
Perceptual Speech Quality Measurement

65
IP Telephony v1.0
Signaling Systems

66
IP Telephony v1.0
T1 Digital Signal Format

67
IP Telephony v1.0
Robbed-Bit Signaling

68
IP Telephony v1.0
Channel Associated Signaling—T1

69
IP Telephony v1.0
E1 Framing and Signaling

70
IP Telephony v1.0
Channel Associated Signaling—E1

71
IP Telephony v1.0
Common Channel Signaling

72
IP Telephony v1.0
ISDN
• 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
IP Telephony v1.0
ISDN Network Architecture

74
IP Telephony v1.0
Layer 3 (Q.930/931) Messages

75
IP Telephony v1.0

1.Introccnamahdys.ppt

More Related Content

Similar to 1.Introccnamahdys.ppt

More from MahmoudElmahdy32

Recently uploaded

1.Introccnamahdys.ppt