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Our most commonly asked questions are:
 How do you call for help?
 What is an emergency?
 What is 911?
 What is the Emergency Alert System (EAS)?
 How does a cell phone work?
 What is a cell phone tower?
 What year were cell phones invented?
 What do the numbers in a phone number do?
 What is Digital Television (DTV)?
 How does a radio work?
 What is the difference between AM radio and FM radio?
 What is Cable Television?
 Why is the 555 exchange used on television shows?
 What is a Satellite?
 What is Broadband?
 How does someone with a hearing disability use a telephone?
 What is Telecommunications Relay Service?
 Can People with Hearing Aids use Standard Telephones?
 What is Video Relay Services?
 What do the end of the Web addressess stand for?
 What is a Satellite dish?
 How do Descramblers work?
 Do cell phones cause brain cancer?
 What is a V-Chip?
 How does a V-Chip work?
 What is unacceptable language for radio and television?
 What is Obscene Speech?
 Why do all FM radio stations end in an odd number?
 How does my pager work?
 How does a fax machine work?
 Why can't you use cell phones in hospitals or airplanes?

ringing 911 telephone How do you call for help?
To call for help dial 9-1-1 on any phone that is working, you will be connected to an emergency operator, called a dispatcher. The dispatcher immediately connects you to the person that can help. 9-1-1 emergency services should be used to report a crime in progress or a fire, or to request an ambulance. 9-1-1 should be used only when you have an emergency. Using 911 for non-emergency calls may delay the arrival of help for people caught in real emergencies.
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Emergency Hospital sign What is an emergency?
An emergency is when there is danger (like a fire), or when someone is badly hurt. Don't let the word scare you. You can be a big help when there is danger or when someone is hurt – just dial 9-1-1 . If you have questions about what an emergency is, it is best to talk to your parents or another adult.
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911 operator What is 911?
Dialing 9-1-1 on your home phone is the fastest way you can get help for yourself or someone else. 9-1-1 was put into operation in 1968 as the number to call for emergency help anywhere in the United States to make getting emergency help faster and easier.

Before 9-1-1 was put into operation, in an emergency people had to find the right phone number in the phone book or through an operator. If there was a fire, people phoned the fire department. If there was a crime, people called the police. If someone got hurt, an ambulance had to be called. Finding a number for any of these emergency services could be very confusing, especially if the person calling was in a hurry or in an unfamiliar area. But today, you only need to know one number for emergency help. You can reach the fire department, the police, or an ambulance by simply dialing 911. For more information about 9-1-1 visit http://kidshealth.org/kid/watch/er/911.html.

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EAS alert on TV What is the Emergency Alert System (EAS)?
The Emergency Alert System (EAS) is a national public warning system that requires TV broadcasters, radio broadcasters, cable television systems, satellite television providers and many others to offer the ability to get information to as many people as possible in the U.S. during a national emergency. The EAS system may also be used by state and local authorities to deliver important emergency information such as AMBER (missing children) alerts and emergency weather information for specific areas. The FCC works with the Federal Emergency Management Agency (FEMA) and the National Weather Service (NWS) to implement EAS at the federal level. The FCC’s goal is to make the EAS capable of distributing emergency information as quickly as possible to as many people as possible.
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cell phone and towerHow does a cell phone work?
A cell phone is a special type of phone that is not connected to your telephone in the house and works both inside and away from your house. For example, you can use a cell phone to make and receive calls in your car, at the park, at the mall, or even at the beach. A cell phone turns your voice into a special type of electricity and sends it over the air to a nearby cell tower; the tower sends your voice to the person you are calling. Cell phones work well when they are near cell towers, but not so well if they are too far away from a cell tower. Cell phones are important because they let us keep in touch with our families when we are away from the house, and can be used almost anywhere to make 9-1-1 calls in case of an emergency. Some cell phones have games you can play; some let you send email or send instant messages to your friends; and some let you take pictures and send them to people.
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cellular tower What is a cell phone tower?
A cell phone tower acts like an antenna. It picks up the call from your cell phone and sends it to the person you are calling so that you can talk to them.
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What year were cell phones invented?
In 1973 Martin Cooper invented the first cell phone. It weighed two pounds! Because they were so big and expensive, at first cell phones were only used by the military and businesses. By 1983 they were smaller and much less expensive and used by more people in the general population.
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What do the numbers in a phone number do?
The telephone number that you dial to call somebody is an address, similar to the street address of your home. In the United States, all phone numbers have a total of 10 digits. The numbering plan was developed by AT&T in 1947. It uses three blocks of numbers - two blocks of three digits and a single block of four digits. It is used for wirelane and cell phones.
Area code Prefix Line number
301 555 0703

Area code – A different area code is assigned to each specific geographic region in the United States, such as a city or a part of a state. In the example above, the geographic region “301” is part of Maryland. Area codes are assigned by the US Government.
Prefix – The first 3 digits of what you think of as your phone number are called the prefix. This prefix originally referred to the specific telephone company switch that a phone line connected to. Each switch at a phone company's central office had a special three-digit number.
Line number – The last four digits of your phone number is called the line number. It is the number assigned to the phone line that runs into your home or a business. The line number is assigned to the phone line and not to the phone you are using. Because the phone number is not assigned to the phone, the phone can be changed and you can even add more phones to the same line.
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digital tv What is Digital Television (DTV)?
Digital Television is a new system of bringing TV signals to your TV set. The DTV signals sent from TV stations are in digital modulation format rather than in the analog modulation format which has been used since television began. You can see digital TV sets on sale at most electronics and large appliance stores right now. They are the ones with the wide screens similar in shape to the screen in a movie theater. Most of these DTV sets are still pretty expensive but the prices are coming down rapidly. DTV allows TV stations to provide you with new and different services that were not available with the old analog system. Probably the most important DTV service is the delivery to your home of High Definition TV (HDTV) signals. Pictures on a DTV set with an HDTV signal provide you with an unusually bright, clear, sharp and lifelike picture in a wide screen format with surround sound audio capability. All full-power TV broadcast stations were required to switch from analog to digital broadcasting by June 12, 2009.
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image of radioHow does a radio work?
Radio signals are made up of two kinds of waves: “audio” (or sound) waves represent the sounds being sent to the audience and radio frequency waves travel with these sound waves to "carry" them to radios in homes and car, for example. All waves have three parts: a wavelength, an amplitude and a frequency. Each of these parts can be changed to carry information.
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AM and FM radio waves What is the difference between AM radio and FM radio?
AM stands for “amplitude modulation” – a type of signal. With AM, the amplitude of the combined audio frequency and radio frequency waves varies to match the audio signal. AM radio can develop problems with interference. This makes it hard to hear the radio show. Interference can be caused by many sources. For example, sparks discharge when a car is started, in electric motors in all sorts of electrical appliances, and even lightning. All of these things can produce interference to AM radio. As you can see, there is a lot of background noise that changes the amplitude of the radio wave signal. This creates the random crackling noises call static.
FM stands for “frequency modulation”- a type of radio transmission, the frequency of the combined waves change to reproduce the audio signal. For example, higher frequency is associated with the peak amplitude in the audio wave. FM waves do not have a problem with interference because the noise background does not modify the radio wave frequency. In addition FM waves give better sound reproduction.

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cable tv What Is Cable Television?
Cable television is a type of delivery system for video programming. It is provided by a cable operator to people that pay for it - called “subscribers”. The video program is sent to the subscriber’s television using coaxial cable or fiber optics. Cable companies often use coaxial cable to transmit or send television shows to your television. Coaxial cable is a wire with a stiff copper as the core, surrounded by an insulating material to protect the wire. This insulation is covered by a conductor, which often consists of a closely woven braided mesh. The conductor allows the video signal to move through the coaxial cable and into your television set. The conductor is protected by a plastic covering.
Fiber Optic lines or optical fibers can also be used as a delivery system for cable video programming. They are made of glass, which is made from sand or silicon and other, inexpensive raw material. The glass used for modern fibers is so transparent that if the oceans were full of it instead of water, the seabed would be as visible from the surface as the ground is visible from an airplane on a clear day. Video programming can also be delivered without a wire via satellite "cable television" under the Commission's definitions.

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Why is the 555 exchange used on television shows?
You may have noticed that, when characters in television shows use a telephone number the prefix is always 555. 555 is used only on television shows and is not a prefix to a real telephone number. This “fake” prefix ensures that a viewer can not dial the number and bother the subscriber to whom that telephone number is assigned. Fictitious numbers for movies and television use 555-0100 to 555-0199. Before the 555 exchange was established, prefixes such as GRAMERCY, PLAZA or KLONDIKE were used.
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image of earth and satelliteWhat is a Satellite?
A satellite is basically any object that revolves around a planet in a circular or elliptical path or orbit. The moon is Earth's original, natural satellite, and there are many manmade (artificial) satellites, their orbits are usually closer to Earth. Satellite service is the only broadband technology that is able to reach virtually any part of the United States. Television viewers are familiar with the concept of satellite dishes that receive TV channels. It can be used to carry phone calls, and radio signals, as well as video programs and internet service and are within the category of communications services called “broadband” services. Other broadband data is delivered in exactly the same way. For many rural areas of the United States, and especially Alaska, satellite service is the only way that residents and businesses will ever have access to the Internet and to other broadband services. Satellite is currently the most expensive way to deliver telecommunications and broad band services like Internet access.
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What is Broadband?
The term “broadband” refers to telecommunication in which a wide band of frequencies is available to transmit information. It is frequently used as another term for high-speed Internet access which allows users to access the Internet and Internet-related services at significantly higher speeds than traditional modems like a regular telephone line. High-speed Internet allows users access to advance data processing and high-speed transmission technologies such as: cable modem; wireless access, satellite access, and power line access. There are many advantages to broadband, some of these are: your connection is always on, there is no need to dial-up your Internet provider; information can be downloaded into our computer at significantly higher speeds than with traditional modems; users can go on line without tying up their telephone lines.
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image of a TTY telephone How does someone with a hearing disability use a telephone?
A text telephone (TTY) allows a deaf, hard-of-hearing or speech-disabled person to make a telephone call. The TTY is a telephone that looks like a typewriter with a text screen – the TTY is connected to the telephone line in the users home or business. Once the telephone connection is made the TTY user types his message to the called party and the words appear on the TTY screen. The called party responds to the caller by typing on his TTY- all conversation is printed on the screen. Instead of listening to what the other person on the phone call says deaf, hard-of-hearing or speech disabled people reads what the person said. The TTY allows a person with a hearing disability to directly call another person who has a TTY. Persons using a TTY may also call any standard phone user by placing the call through a Telecommunications Relay Service.
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What is Telecommunications Relay Service?
Telecommunications Relay Service (TRS) is provided over the telephone line and allows persons with hearing and speech disabilities to communicate by telephone with persons who may or may not have such disabilities. TRS facilities have special equipment and are staffed by communications assistants (CAs) who relay conversations between people who use text telecommunications devices and people who communicate by voice. The caller can use a text telephone (TTY) to dial the telephone number of the local TRS center. For the TTY user, the first step – the inbound call to the TRS center – is functionally equivalent to receiving a dial tone. The CA in turn places an outbound voice call from the TRS center to the called party. The CA serves as the link in the conversation, converting all typed TTY messages from the TTY caller into voice messages, and all voice messages from the called party into typed messages for the TTY user. The process is performed in reverse when a voice telephone user initiates the call to a TTY user.
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Can People with Hearing Aids Use Standard Telephones?
The Hearing Aid Compatibility Act of 1988 (HAC Act) requires that the Federal Communications Commission (FCC) ensure that all telephones manufactured or imported for use in the United States after August 1989, and all "essential" telephones are hearing aid compatible. "Essential" phones are defined as "coin-operated telephones, telephones provided for emergency use, and other telephones frequently needed for use by persons using such hearing aids." These might include workplace telephones, telephones in confined settings (like hospitals and nursing homes), and telephones in hotel and motel rooms. Secure telephones, as well as telephones used with public mobile and private radio services, are exempt from the HAC Act.
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sign language What is Video Relay Service?
This type of Telecommunications Relay Service enables individuals who use sign language to make relay calls through Communications Assistant (CA) who can interpret their calls. To use video relay service the telephone call is made over the internet and uses video equipment so the CA and the caller can see each other. The caller uses sign language to tell the CA who to call and what to say. The CA voices what is signed to the called party and signs back to the caller. This type of relay service is not required by the FCC, but is offered on a voluntary basis by certain TRS programs. This option is helpful for people who use American Sign Language (ASL), and for people who cannot type on a TTY easily, such as children who are ASL users. Video Relay Service is another type of Telecommunications Relay Service that allows persons with hearing and speech disabilities to use the telephone.
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dot com balloon What do the end of Web addresses stand for?
In the United States, there are five main web page endings. These are intended to tell you where the information you are looking at: comes from: ".edu" for educational institutions, ".gov" for government agencies, ".org" for non-profit organizations, ".com" for commercial or business sites, and ".net" for network providers.
In countries outside the United States, the Web addresses end with the country’s abbreviation, such as ".uk", which means that the web site comes from the United Kingdom.

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satellite dish What is a satellite dish?
The dish is the part of satellite TV that you see the most. It is a reflector which is usually made out of aluminum. Dish sizes vary from small (3-4 feet) all the way to 16-20 Ft with the average falling between 7-12 ft, 10 ft being most common. This device focuses the microwave signals coming from the satellites much as the mirror in a reflecting telescope concentrates the light from distant galaxies.
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How Do Descramblers Work?
Each device has a unique ID number, which you give to programming services to subscribe to a channel or package. The programming service broadcasts your ID number, and a special code that instructs your descrambler to work when tuned to a subscribed channel.
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Do cell phones cause brain cancer?
There is no scientific evidence to date that proves that wireless phone usage can lead to cancer or a variety of other health effects, including headaches, dizziness or memory loss. However, studies are ongoing and key government agencies, such as the Food and Drug Administration (FDA) continue to monitor the results of the latest scientific research on this topic. In 1993," the FDA, which has primary jurisdiction for investigating mobile phone safety, stated that it did not have enough information at that time to rule out the possibility of risk, but if such a risk exists, "it is probably small." The FDA concluded that there is no proof that cellular telephones can be harmful, but if individuals remain concerned several precautionary actions could be taken, including limiting conversations on hand-held cellular telephones and making greater use of telephones with vehicle-mounted antennas where there is a greater separation distance between the user and the radiating antennas. The Web site for the FDA's Center for Devices and Radiological Health provides further information on mobile phone safety: www.fda.gov/cellphones/.
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"v" chip What is a V-Chip?
The V-chip is a technology that lets parents block television programming they don't want their children to watch. http://www.fcc.gov/parents/
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tv ratings How does a V-Chip work?
The V-Chip electronically reads television-programming ratings and allows parents to block programs they believe are unsuitable for their children. (Ratings appear in the corner of your television screen during the first 15 seconds of a program and in TV programming guides). This rating is encoded into the program, and the V-chip technology reads the encoded information and blocks shows accordingly. Using the remote control, parents can program the V-chip to block certain shows based on their ratings.
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What is unacceptable language for radio and television?
It is a violation of federal law to broadcast obscene programming at any time. It is also a violation of federal law to broadcast indecent programming during certain hours. Congress has given the Federal Communications Commission (FCC) the responsibility for administratively enforcing the law that governs these types of broadcasts. The Commission may revoke a station license, impose a monetary forfeiture, or issue a warning, for the broadcast of obscene or indecent material.

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people swearing and fighting What is Obscene Speech?
Obscene speech is not protected by the First Amendment and cannot be broadcast at any time. To be obscene, material must meet a three-prong test: (1) an average person, applying contemporary community standards, must find that the material, as a whole, appeals to the prurient interest; (2) the material must depict or describe, in a patently offensive way, sexual conduct specifically defined by applicable law; and (3) the material, taken as a whole, must lack serious literary, artistic, political, or scientific value.
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Why do all FM radio stations end in an odd number?
FM radio stations all transmit in a band between 88 megahertz (millions of cycles per second) and 108 megahertz. The band is divided into 100 channels, each 200 kHz (0.2 MHz) wide. The center frequency is located at 1/2 the bandwidth of the FM Channel, or 100 kHz (0.1 MHz) up from the lower end of the channel. For example, the center frequency for Channel 201 (the first FM channel) is 88.0 MHz + 0.1 MHz = 88.1 MHz. So there can be a station at 88.1 megahertz, 88.3 megahertz, 88.5 megahertz, and so on. The 200-kilohertz spacing, and the fact that they center on odd numbers is completely arbitrary and was decided by the FCC. In Europe, the FM stations are spaced 100 kilohertz apart instead of 200 kilohertz apart, and they can end on even or odd numbers.
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image of pagerHow does my pager work?
A pager is like a FM radio that is tuned to one frequency. (The FCC assigns each paging company specific radio frequencies on which to broadcast their paging signals.) Your pager will "listen" for a unique code within this paging signal. When the code reaches you and your pager "hears" its signal, it decodes it and displays the numeric or word message for you. The frequency of a pager is not within the broadcast bands, and cannot be heard on a regular radio.
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image of fax machineHow does a fax machine work?
The idea of fax machines has been around since 1842, when Alexander Bain invented a machine capable of receiving signals from a telegraph wire and translating them into images on paper. Fax machines provide an easy way to send document to any phone number equipped with a fax machine. A fax machine works by scanning each outgoing page, converting the image into a series of light and dark dots. This pattern is then translated into audio tones, and sent over regular phone lines. The receiving fax "hears" the tones, pieces the grid together, and prints the total number of dots. The resulting document is a black and white likeness of the original page.
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cell phones restricted Why can’t you use cell phones in hospitals or airplanes?
Some of the places that you should never use your mobile phone are inside hospitals and airplanes. When you make or receive calls, electromagnetic waves are sent through the air. Hospitals have a lot of electronic devices that monitor patient's heartbeats and other thing when they are getting surgery or when they are recovering from an illness. When electromagnetic waves try to go through them, the devices sometimes stop working. You can imagine how bad that would be for doctors and nurses in hospitals who are trying to save lives. That's why we should never use mobile phones inside of a hospital.
It's the same thing in airplanes because they use computers to fly through the air. If the computers don't work properly, the airplane may not go the right direction or fly at the right height, or they may even crash! Next time you get on a plane, make sure you turn off your mobile phone so everyone can have a safe flight.

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factoid header
On April 3, 1973, Martin Cooper made the first cellular phone call.



last reviewed/updated on 08/13/09 

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