Telephone /VoIP

www.convergencetechnologycenter.org DUE 402356

Telephone /VoIP

Learning Activity 4

Learning Outcomes 1 and 5

www.convergencetechnologycenter.org

Telephony / VoIP

Differentiate and describe POTS vs. VoIP delivery.

Identify and troubleshoot common issues.


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


Telephone Subsystem

Delivers telephone services to home Design follows local codes and standards Demarcation

Telephone enters home Service distributed to home SP responsibility stops


Low-Voltage

Telephone Cat 3

FCC required minimum for phone lines Older homes

Cat 5 Newer constructions Recommended by ANSI/TIA/EIA-570-A

Scalable Expanded for VoIP


Tip and Ring

Early telephone Switchboard plugs inserted into receptacle

Tip of plug = 1 conductor Ring = other conductor “Tip and Ring”

Colors of Tip White Red Black Yellow Violet

Colors of Ring Blue Orange Green Brown


Wire Pairs and Color Codes 4 Pair cable such as CAT 5

Primary color is tip = white with tracer White wire = tip = first wire of pair to be punched down

Ring = Solid color Wire Pairs

Pair 1 - Blue White/Blue Blue

Pair 2 - Orange White/Orange Orange

Pair 3 – Green White/Green Green

Pair 4 White/Brown Brown


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.


Telephony / VoIP

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.


Telephony / VoIP

VoIP Data (Packets) are moved via Internet Protocol (IP) from LAN to LAN.

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.


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.


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


Telephony / VoIP

Soft phonesAn 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)


Telephony / VoIP

POTS

1. Cross talk

2. Radio interference

3. Dead ports

4. REN (Ringer Equivalence Number)


Telephony / VoIP

Crosstalk:

..speech or signaling tones leaking from other people's connections

..a signal affecting another nearby signal


Telephony / VoIP

Radio Interference:

..disturbance caused in a radio receiver or other electrical circuit by electromagnetic radiation emitted from an external source


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


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


Telephony / VoIP Describe and define fundamentals of

telephone systems


Troubleshooting

Steps to troubleshoot problems Observe symptoms Isolate cause Check connections Test hardware Test software


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)



Solutions:

-- Make sure phone is working,

-- Connect in several phone jacks

-- Check for a dial tone



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.


Troubleshooting VoIP

VoIP – Telephones

The phone does not work.

Solution:

No Power No IP address Software issues


Telephone vs. VoIP: Summary

o The Analog Telephone System (POTS) has been in existence for over 130 years.

o Digital Telephone Transmission has improved voice quality and added other special features.

o The Public Switched Telephone Network provided a central exchange of connecting private networks to the public network.

o Digital Telephone transmission is being expanded into the Internet as VoIP.

o The analog telephone is still used in many households.o The analog telephone is a voice device with a speaker, microphone,

and digital keypad.


Telephone vs. VoIP: Summary

Telephone: Old Technology Reliable Good Sound Quality Relative Inexpensive

VoIP: New Technology Becoming popular

Many added features Lower cost


Questions and Contacts

Julian Carranza, [email protected] Eliazar Martinez, [email protected]

This material is based upon work supported by the National Science Foundation underGrant 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

Telephone /VoIP

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