Transcript Telephony / VoIP

Telephone /VoIP
Learning Activity 4
Learning Outcomes 1 and 5
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DUE 402356
Telephony / VoIP
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Differentiate and describe POTS vs. VoIP
delivery.
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Identify and troubleshoot common issues.
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Telephony / VoIP
Analog
1.
Plain Old Telephone Service (POTS)
2.
Most home telephones still use analog devices connected to
analog phone lines
3.
Signals move relatively slowly when carried in physical media such
as copper wire and cable
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Telephone Subsystem
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Delivers telephone services to home
Design follows local codes and standards
Demarcation
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Telephone enters home
Service distributed to home
SP responsibility stops
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Low-Voltage
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Telephone
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Cat 3
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FCC required minimum for phone lines
Older homes
Cat 5
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Newer constructions
Recommended by ANSI/TIA/EIA-570-A
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Scalable
 Expanded for VoIP
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Tip and Ring
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Early telephone
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Switchboard plugs inserted into receptacle
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Colors of Tip
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Tip of plug = 1 conductor
Ring = other conductor
“Tip and Ring”
White
Red
Black
Yellow
Violet
Colors of Ring
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Blue
Orange
Green
Brown
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Wire Pairs and Color
Codes
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4 Pair cable such as CAT 5
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Primary color is tip = white with tracer
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White wire = tip = first wire of pair to be punched down
Ring = Solid color
Wire Pairs
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Pair 1 - Blue
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Pair 2 - Orange
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White/Orange
Orange
Pair 3 – Green
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White/Blue
Blue
White/Green
Green
Pair 4
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White/Brown
Brown
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Telephony / VoIP
Frequency Division Multiplexing
1.
The process of allowing analog lines the capability to carry multiple
conversations or data streams at the same time.
2.
Made possible by dividing analog frequencies on a line and sharing
them among different voice and data lines
3.
Multiple telephone lines are possible on home and businesses
without the additional cost of adding more wires.
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Telephony / VoIP
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Centrex System
Central Switching Exchange, used by organizations
having telephones in many locations
A telephone line would have many extensions,
but only one call could be made at a time.
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Telephony / VoIP
VoIP
Data (Packets) are moved via Internet Protocol (IP)
from LAN to LAN.
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Voice can travel on same LAN network.
Systems require special hardware, configuration and
settings in quality to meet the same standards set forth by
the Telephone System.
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Telephony / VoIP
Voice over IP (VoIP)
Packets must be received and reassembled
into the order they were sent, voice
decoded from digital to analog and sent to
the phone speaker, all without any time lags
or delays.
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Telephony / VoIP
Digital
Faster data/voice transfer rates
Packets are used as the transport of
digital signals
Use Protocols to set standards,
… i. e. Addressing, Errors, Control
Uses zeros and ones, making it easy
to read and duplicate
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Telephony / VoIP
Soft phones
An application (software) written to act as a telephone with a computer.
The soft phone:
Displays phone features
Hold Button
Caller ID
Message waiting light
Other features
Routes calls with use of a headset or special (USB) phone
connection
Works with minimum PC hardware requirements
Provides same functionality as the PC. (Remote, mobility)
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Telephony / VoIP
POTS
1.
Cross talk
2.
Radio interference
3.
Dead ports
4.
REN (Ringer Equivalence Number)
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Telephony / VoIP
Crosstalk:
..speech or signaling tones leaking from
other people's connections
..a signal affecting another nearby signal
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Telephony / VoIP
Radio Interference:
..disturbance caused in a radio
receiver or other electrical circuit by
electromagnetic radiation emitted
from an external source
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Telephony / VoIP
Ringer Equivalence Number (REN)
..a somewhat arbitrary number which
denotes the electrical load a telephone
ringer has on the line
REN – in the US considered a yardstick
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Telephony / VoIP
PBX
Private Lines Switch System
Usually is considered the demarcation point or
demark between the owner and the Telephone
Company.
A device used to route calls from the owners
equipment (PBX) to the public telephone system
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Telephony / VoIP
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Describe and define fundamentals of
telephone systems
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Troubleshooting
Steps to troubleshoot problems
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Observe symptoms
Isolate cause
Check connections
Test hardware
Test software
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Troubleshooting Telephones
Possible Telephone problems:
Inconsistent ringing of phone,
Can not hear / or be heard,
Dialing wrong number
Solutions: The handset, the telephone base,
wiring, or Telephone Co. (software)
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Troubleshooting Telephones
Solutions:
-- Make sure phone is working,
-- Connect in several phone jacks
-- Check for a dial tone
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Troubleshooting Telephones
Power Limits: The phone has a limited
amount of power available from the phone
company to make your phones ring
Solution:
Exceeded REN - Remove a
phone.
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Troubleshooting VoIP
VoIP – Telephones
The phone does not work.
Solution:
No Power
No IP address
Software issues
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Telephone vs. VoIP:
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Summary
The Analog Telephone System (POTS) has been in existence for
over 130 years.
Digital Telephone Transmission has improved voice quality and
added other special features.
The Public Switched Telephone Network provided a central
exchange of connecting private networks to the public network.
Digital Telephone transmission is being expanded into the Internet
as VoIP.
The analog telephone is still used in many households.
The analog telephone is a voice device with a speaker, microphone,
and digital keypad.
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Telephone vs. VoIP:
Summary
Telephone:
Old Technology
Reliable
Good Sound Quality
Relative Inexpensive
VoIP:
New Technology
Becoming popular
Many added features
Lower cost
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Questions and Contacts
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Julian Carranza, [email protected]
Eliazar Martinez, [email protected]
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This material is based upon work supported by the National Science Foundation under
Grant No. 0402356. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the National Science Foundation