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GSM
Global System for Mobile Communications or GSM is the digital transmission technique widely adopted in Europe and supported in North America for PCS. GSM uses the 1900 MHz. GSM uses 900 MHz and 1800 MHz in Europe. See also CDMA , PCS , TDMA.

HZ (Hertz)
The unit of frequency measurement equal to one cycle per second. Abbreviated Hz and named after Heinrich R. Hertz. See also MHz (Megahertz).

Hands-Free Operation/Handling
Using a wireless phone without having to lift or hold the phone to your ear.

IMEI
The International Mobile Equipment Identifier (IMEI) is a 15-digit number (composed of four parts) that uniquely identifies an individual wireless phone or communicator. The IMEI appears on the label located on the back of the phone. The IMEI is automatically transmitted by the phone when the network asks for it. A network operator might request the IMEI to determine if a device is in disrepair, stolen or to gather statistics on fraud or faults.

Incoming Call
A call placed by another party to your wireless phone. In virtually all current wireless phone service plans, the owner of the wireless phone pays for all calls, both incoming (calls from others) and outgoing (placed by you).

Internet Capability
Refers to a wireless communication device that is capable of Internet functions such as e-mail (send, receive, forward or reply) and browsing the World Wide Web.

Keyguard
The keyguard feature provided on some mobile phones allows the user to disable the keys so that a number will not accidentally be dialed while the phone is in your pocket or purse.

LCD Screen
Liquid Crystal Display screens have low energy requirements and are generally easy to read. LCD screens are made by sealing a liquid compound between two pieces of glass and/or a filter. The screen has hundreds or thousands of dots that are charged or not charged which make them reflect or not reflect light to form letters, characters and numbers. Some LCD screens have an electroluminescent panel behind them and are termed "backlit."

Li-Ion
Refers to a type of battery, a Lithium-Ion battery, used to power wireless communication devices. Li-Ion batteries are lighter weight than earlier battery types, have a relatively long cycle life and generally do not suffer from memory effect. See also Battery , Memory Effect , NiCd , NiMH.

Local Service Area
The geographic area that telephones may call without incurring roaming or long distance charges.

Lock Code
A code that prevents a wireless phone from unauthorized use. It is programmed into the Numerical Assignment Module or NAM. A lock code is used in conjunction with the phone lock feature. When activated, the phone will lock after you switch your phone off and back on. Each time the phone is turned on, it will prompt you to enter a lock code before it will allow a call to be placed, or to access most of the phone's memory and menu features. Calls, such as emergency or other numbers programmed as unlocked phone numbers may be placed without entering a lock code.

MHz (Megahertz)
A unit of frequency equal to one million hertz or cycles per second. Wireless communications occur in the 800 MHz, 900 MHz and 1900 MHz bands. See also Band , HZ (Hertz).

MIN
The Mobile Identification Number (MIN) is a unique 24-bit number assigned by the wireless service provider to each phone it sells or includes in service plans. Unlike an Electronic Serial Number (ESN), a MIN is changeable because wireless phones may change hands or phone owners may move to another coverage region, requiring a different service plan. The MIN and ESN are both automatically transmitted to the wireless network each time the phone is used to verify that the phone has not been reported lost or stolen and that all subscriber bills are current. See also ESN.

MMM
Mobile Media Mode (MMM) products have the ability to provide information services such as stock quotes, flight information and reservations, news, sports, weather updates, and even access to e-mail wirelessly. Check with your local cellular service provider to find out when services will be available in your area.

MTAs/RSAs
Metropolitan Trading Areas (MTA) are areas of economic integration defined by Rand McNally's Commercial Atlas. The FCC uses the 51 U.S. MTAs as the boundaries for PCS licenses. Each MTA consists of several Basic Trading Areas (BTAs) which are several contiguous counties. The FCC also identified 428 rural U.S. markets or Rural Service Areas. Two service providers are licensed for each RSA. See also FCC.

Memory Effect
The life of a battery may be gradually shortened if it is recharged before it is completely discharged. Memory effect most commonly occurs with Nickel Cadmium batteries, is less of a problem with Nickel Hydride batteries and even less with Lithium Ion batteries.

Messaging
Using various products, services and technologies to transfer messages from one person to another, or from one device to another such as traditional numeric or alphanumeric paging, e-mail or short messages (SMS) delivered to wireless devices. See also SMS.

Mobile Phone
A term often used interchangeably with cellular phone or wireless phone. Initially, a mobile phone referred to a phone attached to a vehicle, the vehicle's battery and had an external antenna. Mobile phones were distinguished from transportable, portable, cordless and personal phones. See also Transportable Phones.

Modulation
The process of coding and decoding information for transmission. For example, a voice conversation is coded into binary bits (digital information), transmitted and then decoded at the receiving end.


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