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1 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony Introduction to Packet Voice Technologies Cisco Networking Academy Program
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2 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Traditional Telephony
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3 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Basic Components of a Telephony Network
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4 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Central Office Switches
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5 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 What Is a PBX?
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6 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Basic Call Setup
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7 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Supervisory Signaling
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8 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Address Signaling Tone telephone DTMF dialing Rotary telephone –Pulse dialing
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9 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Informational Signaling
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10 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Digital vs. Analog Connections
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11 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Time-Division Multiplexing
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12 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Frequency-Division Multiplexing
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13 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Packetized Telephony Networks
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14 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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
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15 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Call Control
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16 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Distributed Call Control
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17 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Centralized Call Control
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18 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Packet Telephony Components
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19 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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.
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20 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Foreign Exchange Station Interface
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21 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Foreign Exchange Office Interface
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22 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Interface
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23 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 T1 Interface
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24 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E1 Interface
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25 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 BRI
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26 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Physical Connectivity Options
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27 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Cisco IP Phone
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28 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Analog Voice Basics
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29 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Local Loops
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30 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Types of Local-Loop Signaling Supervisory signaling Address signaling Informational Signaling
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31 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 On Hook
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32 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Off Hook
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33 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ringing
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34 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ringing (Cont.)
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35 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Pulse Dialing
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36 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Dual Tone Multifrequency
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37 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Informational Signaling with Call-Progress Indicators
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38 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunks
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39 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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
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40 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Types of Trunk Signaling Loop start Ground start E&M Wink Start E&M immediate start E&M delay start
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41 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Loop-Start Signaling
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42 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ground-Start Signaling
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43 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Signaling Separate signaling leads for each direction E-lead (inbound direction) M-lead (outbound direction) Allows independent signaling
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44 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type I
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45 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type V
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46 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type II
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47 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type III
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48 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type IV
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49 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Wink Start
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50 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Immediate Start
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51 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Delay Start
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52 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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.
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53 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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.
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54 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Echo Suppression
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55 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Echo Cancellation
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56 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Analog-to-Digital Voice Encoding
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57 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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.
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58 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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.
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59 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Nyquist Theorem
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60 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Voice Compression Techniques Waveform algorithms PCM ADPCM Source algorithms LDCELP CS-ACELP
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61 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public 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 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
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62 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Compression Bandwidth Requirements
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63 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Mean Opinion Score
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64 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Perceptual Speech Quality Measurement
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65 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Signaling Systems
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66 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 T1 Digital Signal Format
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67 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Robbed-Bit Signaling
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68 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Channel Associated Signaling—T1
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69 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E1 Framing and Signaling
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70 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Channel Associated Signaling—E1
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71 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Common Channel Signaling
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72 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 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
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73 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 ISDN Network Architecture
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74 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Layer 3 (Q.930/931) Messages
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75 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0
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