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Glossary of Terms
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"A" Carrier: See non-wireline cellular company.
A/B switch: A feature found on cellular telephones permitting the user to select either the "A" (non-wireline) carrier or the "B" (wireline) carrier when roaming away from home.
Air Time: Actual time spent talking on the cellular telephone.
AMPS: Advanced Mobile Phone Service, or as referred to as the analog cellular system, uses cellular phones to communicate via radio signals to base stations. The base stations convert radio signals for transfer to a central Mobile Telephone Switching Office(MTSO), land line or other link.
Analog: The traditional method of modulating radio signals so that they can carry information. The only cellular technology that currently works with TTY equipment. AM (amplitude modulation) and FM (frequency modulation) are the two most common methods of analog modulation.
Authentication: The process that enables cellular phones and cellular service providers to confirm the identity of any phone placing or receiving a call, allowing routing of calls, accurate billing, amd inhibiting fraudulent use of the system.
"B" carrier: See wireline cellular company.
Bandwidth: A relative range of frequencies that can carry a signal without distortion on a transmission medium.
Base station: The central radio transmitter/receiver that maintains communications with mobile radiotelephone sets within a given range (typically a cell site). See also Cell.
CDMA: Code Division Multiple Access.
CDPD: Cellular Digital Packet Data. Technology that allows data files to be broken into a number of "packets" and sent along idle channels of existing cellular voice networks.
Cell Site: A radio transmitting station that provides service to cellular telephone subscribers. It converts phone line signals to radio signals for transmission to mobile phones.
Cell splitting: A means of increasing the capacity of a cellular system by subdividing or splitting cells into two or more smaller cells.
Channel: A pair of frequency bands, similar to an FM channel, which allow communication signals to be transmitted.
Commercial Mobile Radio Service: The regulatory classification that the FCC uses to govern all commercial wireless service providers including Personal Communications Services, cellular and Enhanced Specialized Mobile Radio.
Cross Talk: The problem of hearing voices from one channel imposed on another channel.
Dead Spot: An area of weak signal strength due to terrain or other obstructions.
Digital Channel: A radio channel that transmits voice in digital form. Voice data is encoded as a stream of information bits before being converted to a radio signal. After reception, the data is decoded back into sound.
Electromagnetic Compatibility (EMC): The ability of equipment or systems to be used in their intended environment within designed efficiency levels without causing or receiving degradation due to unintentional electromagnetic interference.
Encryption: A system for digitally scrambling voice data so that only a pre-established code can unscramble it, thus adding an extra measure of security to prevent eavesdropping.
ESN: Electronic Serial Number. An 11-digit electronic serial number that identifies each cellular phone to the cellular system.
FCC: Federal Communications Commission. The government agency responsible for regulating telecommunications in the United States.
FDMA: Frequency Division Multiple Access. Method of radio transmission that allows multiple users to access a group of radio frequency bands without interference.
Frequency: A measure of the energy, as one or more waves per second, in an electrical or lightwave information signal. A signal's frequency is stated in either cycles-per-second or Hertz (Hz).
Frequency re-use: The ability to use the same frequencies repeatedly within a single system, made possible by the basic design approach for cellular.
GHz: gigaHertz. Billions of Hertz.
GSM: Groupe Speciale Mobile, now translated in English as Global Standard for Mobile, is the Pan-European digital cellular system standard. It is a time-division based standard for digital wireless transmissions. See also Digital modulation.
Hand-off: Occurs when a cellular phone moves out of one cell site range and into another. The Mobile Telephone Switching Office passes (hands-off) a cellular phone conversation cell-site to the next. It is performed so quickly that callers rarely notice.
Hands-Free: A microphone/speaker accessory system allowing the use of a cellular phone without holding the handset. An important SAFETY feature.
Hertz: A measurement of electromagnetic energy, equivalent to one "wave" or cycle per second.
KHz: kiloHertz (thousands of Hertz).
Message alert: (also called a "call-in-absence" indicator) A light or other indicator on a wireless phone that notifies a user that a call has come in. A useful feature especially if the cellular subscriber has voice mail.
MHz: megaHertz. millions of Hertz.
MTSO: Mobile Telephone Switching Office. The central computer that connects a cellular phone call to the public (land) telephone network.
NAM: Number Assignment Module. The NAM is the electronic memory in the cellular phone that stores the telephone number and electronic serial number.
PCS: Personal Communications Services. FCC terminology describing intelligent, digital wireless, personal two-way communications systems.
POP: Short for population. One "POP" equals one person.
Portable: A small, lightweight handset that transmits at no more than .6 watts of power provided by a small rechargeable battery.
Roaming: The ability to use a cellular phone to make and receive calls in places outside your home calling area.
Sleep Mode: Digital control channel technology allows some phones to power down (sleep) and wake up periodically to check your calls and messaging.
Standby time: The amount of time you can leave your fully charged wireless portable or transportable turned on before the phone's battery will run down. See also Talk time.
Talk time: The length of time you can talk on your portable or transportable wireless phone without recharging the battery. The battery capacity of a phone is usually expressed in terms of "minutes of talk time" or "hours of standby time." When you're talking, the phone draws more power from the battery. See also Standby time.
TDMA: Time Division Multiple Access. A method of digital wireless communications transmission allowing a large number of users to access (in sequence) a single radio frequency channel without interference by allocating unique time slots to each user within each channel. See also Digital modulation.
Transportable: A standard 3-watt mobile phone that can be removed from a car and used by itself with an attached battery pack. The entire unit is generally mounted or built into a custom carrying case to make it easy to carry. Although technically "portable," the transportable should not be confused with the handheld, one-piece wireless phone.
Voice mail: (Also called voice messaging) A computerized answering service that answers a call, plays a greeting and records a message. Depending on the service provider, it also can notify you via a pager that you have received a call.
Wireline Carriers: Cellular providers that also provide land telephone service carried through wires.
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