Airtime
Actual time spent talking on your cellular telephone. In general most cellular phone companies charge you from the time you hit the SEND button until you hit the END button (i.e. you pay to listen to a ringing signal). GSM phone companies (e.g. Fido, Cityfone) generally charge actual talk time and not time listening to ringing signals. You are not charged for listening to busy signals or if your call is not answered. This puts the '100 free minutes' included in your monthly plan into a slightly different perspective than what you're used to with a land line.

AMPS
Advanced Mobile Phone Service; commonly known as analog cellular. Offered in the 800 MHz spectrum by both Mobility and Rogers AT&T. AMPS service has been available in Canada since the mid 80's and is also available in the US, Mexico, Australia, and several other countries. Calling this system analog is not really true. Although your voice is transmitted via analog, some of the phone's background operations are digital in nature. AMPS offers limited battery life, poor sound quality, and has a much higher power output rate than the newer digital phones. Available only in the 800 MHz frequency band. Compare this with TDMA, CDMA, GSM, and iDEN.

Base Station
A transmission and reception station for handling cellular traffic. Usually consists of one or more receive/transmit antenna, microwave dish, and electronic circuitry. Also referred to as a cell site, since it holds one or more tx/rx cells. Base stations are constructed and placed on high buildings, hydro towers, monopoles, or other structures with a good elevation above the area to be covered. Several base stations within an area form a wireless network.

In general 800 MHz sites are spaced about 10-12 km (6-8 mi) apart and 1900 MHz sites are spaced about 3-4 km (2-2.5 mi) apart. In high network traffic areas base stations are placed much closer together. Base stations may also be placed closer together to deal with interferce from adjacent buildings and other geographic irregularities. Radio freqencies carry much better over very flat terrian or water so providers can space base stations even farther apart in these areas.
Even a Simpsons episode featured a cellular base station above their house. Mind you, real base stations don't look like this!

CDMA
Code Division Multiple Access; also known as IS-95. One of the newer digital technologies in use in Canada, the US, Australia, and some southeastern Asian countries (e.g. Hong Kong and South Korea). CDMA differs from GSM and TDMA by its use of spread spectrum techniques for transmitting voice or data over the air. Rather than dividing the radio frequency spectrum into separate user channels by frequency slices or time slots, spread spectrum technology separates users by assigning them digital codes within the same broad spectrum. Advantages of CDMA include higher user capacity and immunity from interference by other signals. Available in either 800 or 1900 MHz frequencies.

Cell
The basic geographic unit of a cellular system and the basis for the generic industry term "cellular." A city is divided into small "cells", each of which is equipped with a low-powered radio transmitter/receiver or base station. The cells can vary in size depending on terrain and capacity demands. By controlling the transmission power and the radio frequencies assigned from one cell to another, a computer at the MTSO monitors the movement and transfers or hands off the phone call to another cell and another radio frequency as needed.

Codec
Short for "compressor/decompressor"; refers to the hardware in a cell phone and in the cell network that compresses digitized voice prior to transmission AND takes received compressed voice and decompresses it prior to passing it to either a cell phone speaker or into a wireline system. Codec allows the cell network to essentially pass a lot of data in compressed form to permit additional users on the system and to save bathwidth. The idea behind codec is that human voices are highly lossy and a significant amount of the conversation can be removed since human ears can fill in the removed gaps at the other end. Each technology has different codec algorithms -- for CDMA there is 13K and 8K.

Control Channel
A channel used for transmission of digital control information from a base station to a cellular phone (forward control channel) or from a cellular phone to a base station (reverse control channel).

Dual Band
Dual band phones are capable of using two different frequencies of the same techologies. For example a TDMA or CDMA phone that can use either the 800 or 1900 MHz band. There are also Triple Band phones in the GSM market that support 900, 1800, and 1900 MHz. Dual band phones allow you to access different frequencies in the same or different geographic regions, essentially giving your phone a wider coverage area.

Dual Mode
Dual mode phones that support more that one techology. For example a 800 MHz CDMA phone that also supports 800 MHz AMPS. You can also have phones that support dual band/dual mode such as the Nokia 6185 which is 800, 1900 MHz CDMA and 800 MHz AMPS. Dual mode phones allow you to access different technologies in the same or different geographic regions, essentially giving your phone a wider coverage area.

ESN
Each cellular phone is assigned an unique ESN or Electronic Serial Number, which is automatically transmitted to the cellular base station every time a call is placed. The MTSO validates the ESN with each call. Cloned cellular phones transmit a stolen ESN and charges are made to the real cellular phone account.

Frequency reuse
The ability to use the same frequencies repeatedly across a cellular system, made possible by the basic design approach for cellular. Since each cell is designed to use radio frequencies only within its boundaries, the same frequencies can be reused in other cells not far away with little potential for interference. The reuse of frequencies is what enables a cellular system to handle a huge number of calls with a limited number of channels.

GSM
Global System for Mobile communications. The most common digital cellular system in the world. GSM is used all over Europe, plus many countries in the Middle East, Asia, Africa, South America, Australia, and North America. GSM's air interface is based on narrowband TDMA technology, where available frequency bands are divided into time slots, with each user having access to one time slot at regular intervals. Narrow band TDMA allows eight simultaneous communications on a single radio multiplexer and is designed to support 16 half-rate channels. GSM also is the only technology that provides incoming and outgoing data services, such as email, fax, and internet surfing. GSM makes use of a SIM card that allows memory portability between dumb GSM phones.

Handoff
The process by which the MTSO passes a cellular phone conversation from one radio frequency in one cell to another radio frequency in another. The handoff is performed so quickly that users usually never notice.

Hertz
A unit for expressing frequency which is the number of times a wave-like radio signal changes from maximum positive to maximum negative charge per second. 1 Hz = 1 cycle per second. 1 kilohertz (kHz) = 1,000 Hz; 1 megahertz (MHz) = 1,000 kHz or 1,000,000 Hz; 1 gigahertz (GHz) = 1,000 MHz or 1 million kHz or 1 billion Hz. AMPS (analog) cellular phones in Canada and the US use the 800 MHz band. Digital phones use either the 800 MHz or 1900 MHz (or 1.9 GHz) frequencies. Specifically, CDMA and TDMA use either 800 or 1900 MHz; iDEN uses only 800 MHz; GSM uses only the 1900 MHz spectrum in North America. GSM uses 900, 1800, and/or 1900 MHz on other continents.

iDEN
A modified TDMA technology used by Motorola. iDEN phones operate at 800 MHz and are offered by Clearnet in Canada and by Nextel in the US.

MTSO
Mobile Telephone Switching Office. The central switch that controls the entire operation of a cellular system. It is a sophisticated computer that monitors all cellular calls, tracks the location of all cellular-equipped vehicles traveling in the system, arranges handoffs, keeps track of billing information, etc.

NAM
The NAM or Number Assignment Module is the electronic memory in the cellular phone that stores the telephone number. Phones with dual- or multi-NAM features offer users the option of registering the phone with a local number in more than one market.

Paging
The act of seeking a cellular phone when an incoming call is trying to reach the phone.

PCS
Personal Communication Services. PCS and cellular are sometimes interchanged. Officially, PCS is a digital cellular service in the 1900 MHz band only. In practice, some providers (e.g., Telus Mobility, Rogers) have used part of their AMPS 800 MHz allocation to offer PCS or digital cellular services.

PRL
Referred Roaming List. A list of SID's kept inside a phone to permit roaming on other wireless networks. A service provider may set up roaming agreements with other service providers in different geographic regions and the PRL will try to locate one of these service providers' networks first when the home service provider is unavailable. PRL's do change so it's a good idea to ask for a PRL upgrade every 6 months or so if you do a lot of roaming outside your home service area.

Registration
The procedure that a cellular phone initiates to a base station to indicate that it is now active.

Roaming
The ability to use your cellular phone outside your providers' home service area. Providers often set up Roaming Agreements with other providers in different geographic locations. A roaming agreement lets you seemlessly make calls in the other provider's geographic service area without operator intervention. Roaming agreements save customers money and time. Airtime incurred while roaming shows up on your monthly statement as an additional charge (exceptions: Bell North American Plan, Rogers AT&T digital one rate, and Clearnet Mike).
Roaming is never as cheap as your home airtime rates, but is provided as a short-term convience for a provider's customers. Sometimes a roaming agreement may not be in place and operator intervention is required to obtain a credit card number. This is usually much more expensive than a roaming agreement (up to /min compared to $1/min).
Always contact your provider before roaming. Sometimes phones require roaming to be enabled to prevent fradulent activity (e.g., anyone traveling to New York must have their provider unlock roaming restrictions for the duration of the trip); sometimes you need to know special codes to allow calls to be delivered to your phone; some roaming agreements allow the host provider to charge a daily roaming fee just to have the phone accessing their network; and some other providers charge airtime for the phone ringing even though you choose not to answer it.

SID
System Identification. A five digit number that indicates which service area the phone is in. Most carriers have one SID assigned to their service area.

SIM card
A small memory card not much bigger than half the length of your thumb. Used in GSM phones to hold your phone numbers and other information. Can be removed and inserted into other GSM phones, allowing you to keep your numbers and to place and receive phone calls.

SMS
Short Message Service. A method of delivering a short (120-200 character) message to your digital cellular phone. GSM phones can also send SMS. A nice way to send a short message to someone without calling them. Private SMS services include weather and sports reports, stock quotes, and more. Usually people can either visit a SMS web page and type a short message which is sent to your phone or email your phone (e.g., 2508827626@msg.clearnet.com). Some providers change additional monthly fees for the reception or transmission of SMS. See my Links page for a list of SMS services.

SP-lock
A lock placed on a cellular phone by some service providers to ensure that you can only use the phone with their services. More Information.

Standby time
The amount of time you can leave your fully charged cellular phone turned on before the phone will completely discharge the batteries.

Talk time
The length of time you can talk on your cellular phone without recharging the battery. The battery capacity of a cellular phone is usually expressed in terms of so many minutes of talk time OR so many hours of standby time. When you're talking, the phone draws additional power from the battery.

TDMA
Time Division Multiple Access. TDMA divides frequency bands available to the network into time slots, with each user having access to one time slot at regular intervals. TDMA thereby makes more efficient use of available bandwidth than the previous generation AMPS technology. Available in either 800 or 1900 MHz frequencies.

Voice Channel
A channel used for transmission of voice data from a base station to a cellular phone (forward voice channel) or from a cellular phone to a base station (reverse voice channel)