MAS 102 Midterm exam study guide 3: Principles of Telephony

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Key Telephone Systems:

For the small business user, Permits multiple lines to terminate on one telephone with the punch of a button, Many features are inherent in the system, such as hold and call pickup

The Telephone has five parts

Transmitter Receiver Ringer Control unit Switchhook

International Telecommunications Union Is a

United Nations Agency

There are four primary types of data communications

Voice, data, message, and image

Transmitter

a microphone

Receiver

a speaker

Every telephone line is

a twisted pair of wires (2X)

Ringer

bells, whistles, horns, buzzers, and musical interludes

During times of unusually high use, central offices may be overwhelmed -- this results in

blocking

2X wires connect phones to a

central office

Switching

connecting one circuit to another

Analog Transmission is a

continuous and continuously varying flow of electrical energy that varies with the frequency and strength of the sound

Rotary phones used

dial pulsing signaling

Cellular may be analog or digital, but is primarily

digital since 1997-98

what came after step-by-step system (10,000 users) and panel system (30,000 users)

electronic switching systems, Minimum of 100,000 lines

Single-Line Systems Consist of an

individual line and one or more telephones each line can support several extensions may be residential or small business, but business charges are higher largest market for phone business

Only basic black phones were available until the

late 50s

Each central office serves a

specific geographic area, size depends on the number of lines

Digital Transmission is a

stream of discrete on and off pulses called bits

The central office began as a

switching center

Mathematically no more than

8 million numbers per area code

Cordless Phones

Base station connected to phone line and cordless handset Uses low-power radio transmission Absolutely no expectations for privacy

local loop consist of three parts

Drop wire -- from house to pole to a: Distribution cable -- runs down your street on poles to a: Feeder cable -- connects to the central office

Push-button phones use

Dual Tone Multifrequency

Personal Communications Systems (PCS) are digital

services May be a satellite-based service

Push-button phones are

Necessary for "talking" to computers

Digital transmission is better quality because

No noise and distortion More efficient and faster More economical in the long run

Private Branch Exchanges (PBX)

On-premises computer-based switching system for large organizations Calls between stations are dialed directly, usually with a single-digit prefix Can be purchased, leased, or rented from AT&T, RBOCs and many other vendors

Central Offices

Originally, every phone went from one phone directly to another As the number of phones increased, this became unworkable, plus: Telephones were more valuable if they connected to multiple phones

The Telephone is

The basic instrument of all communications technology

Transmission of Sound

Sound waves are converted to electrical energy, Transmitted over wires or another medium, Converted back to sound, Transmission is an analog signal, Frequency range is from 300 to 3,400 Hz

Voice communication is

Telephony

Switchhook

signals the phone company and caller that the phone is either idle or in use

Trunk lines connect

one central office to another

The central office provides links to

other central offices and to long distance providers

other kinds of communications make heavy use of

phone lines

Control unit

push buttons or rotary dial

Electricity for the phone is delivered via

the 2X wire

Automatic exchanges began to replace operators in

the early 20s

The ITU-T established

world-wide numbering plan


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