Sprint utilizes CDMA technology.
Vz utilizes CDMA technology.
T-Mobile utilizes GSM
Cingular utilizes GSM
Advantages of GSM
GSM is mature, this maturity means a more stable network with robust features.
Less signal deterioration inside buildings.
Ability to use repeaters
Talktime is generally higher in GSM phones due to pulse nature of transmission.
The availability of Subscriber Identity Modules allows to users to switch networks and handsets at will.
GSM covers virtually all parts of world so international roaming is not a problem.
GSM is an open standard, therefore operators do not need to pay royalties to utilize it.
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Disadvantages of GSM
Pulse nature of transmission interferes with some electronics, especially certain audio amplifiers.
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Advantages of CDMA
Capacity is CDMA's biggest asset. It can accommodate more users per MHz of bandwidth than any other technology.
CDMA consumes less power and covers large areas so cell size in CDMA is larger.
CDMA is able to produce a reasonable call with lower signal levels.
CDMA uses Soft Handoff, reducing the likelihood of dropped calls.
CDMA's variable rate voice coders reduce the rate being transmitted when speaker is not talking, which allows the channel to be packed more efficiently.
Has a well-defined path to higher data rates.
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Disadvantages of CDMA
Breathing of base stations, where coverage area shrinks under load.
Most technologies are patented and must be licensed from Qualcomm.
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I can take my Cellphone to Europe, pull my SIM card, buy one in Europe and put it in my phone and it works. Most of the world use GSM. CDMA has it's advantages, but I would not say it is better. Calling area matters most for Cell Phone users.
Having a flat tire on a deserted road in Pennsylvania and picking up your phone to call for help doesn't do any good if your "superior" CDMA system doesn't cover the area.
My "inferior" GSM phone works. For me, that is important if my fiancé, mother, sister, father, or any other loved ones can pick up their phone and get the help they need.
Tom