Gsm Unlocked Cellular Phones

Written by Helen Glenn Court
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As you see references to GSM unlocked cellular phones, it occurs to you again that the terminology floating around digital wireless technology is sometimes a bit confusing. What exactly is GSM? How does locking and unlocking work into the equation? How much should and do you care about any of this?

GSM Unlocked Cellular Phones: An Overview

GSM--or global system mobile communications, originally Globale Spéciale Mobile--is one of three digital wireless technologies behind cellular telephones. It is the standard in Europe, Africa, Asia, and the Pacific Rim. Service is provided on two frequencies, 900 MHz and 1800 MHz, with a removable SIM--subscriber identification module--chipset. All manufacturers and service providers in these countries produce and use only GSM unlocked cellular phones.

In the United States, there are three standards--GSM, TDMA, and CDMA. They are not compatible. Service and customers are linked, not by a SIM chip, but a hardwired phone. The phone belongs, in essence, to the provider. GSM also operates on a different frequency--1900 MHz--than elsewhere, a few South American countries excepted. U.S. phones cannot be used in other countries and vice versa, not without calls costing from $1 to $7 a minute.

This has proved problematic. Manufacturers are producing phones with SIM chipsets that are compatible with all GSM frequencies. U.S. providers, however, are "locking" the phone by computer code so that it will accept only a SIM they supply, keeping control of the phone in their hands. GSM unlocked cellular phones are those you "uncode"--this is entirely legal--so that the phone, for which you have paid several hundred dollars, is yours to use as you see fit, with whatever (non-U.S.) provider you prefer.

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