What the difference between GSM and CDMA mobile phone?  

Hi Gaurav
In cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). Cellular carriers including Sprint PCS, Cingular Wireless, Verizon and T-Mobile use one or the other. Understanding the difference between GSM and CDMA will allow you to choose a carrier that uses the preferable network technology for your needs.

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other.
Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.
Data Transfer Speed: With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies.
EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready.
GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required.
In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance.
Subscriber Identity Module (SIM) cards: In the United States only GSM phones use SIM cards. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention. The SIM itself is tied to the network, rather than the actual phone. Phones that are card-enabled can be used with any GSM carrier.
The CDMA equivalent, a R-UIM card, is only available in parts of Asia but remains on the horizon for the U.S. market. CDMA carriers in the U.S. require proprietary handsets that are linked to one carrier only and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one. The old phone becomes useless.

Answered by jaivir at 1:59 PM on May 07, 2008

well,CDMA and GSM are the names of competing cellular phone standards. They're about equal in the U.S. in terms of users, but overseas there's only GSM other than a few places like Japan, India, and Korea. Out of the four national carriers in the U.S., two -- Sprint and Verizon -- use CDMA, the other two--AT&T and T-Mobile -- use GSM.

The two biggest differences between these standards are international compatibility, and how the networks handle activating phones. Outside the U.S. and Canada, most GSM phones will still work, while almost all CDMA phones simply can't be used overseas. The only ones that can are those that also have a GSM radio. These are sold for people regularly traveling overseas on business, and are priced accordingly.

CDMA phones are activated remotely, by the carrier, using the phone's serial number, known as the ESN. Since each carrier has a database of all the ESNs that are approved for its network, this lets most CDMA carriers refuse to activate phones not originally intended for their network.

GSM phones are activated differently. Each account is associated with what's called a SIM card, or Subscriber Identity Module. This card, about the size of a fingertip and the thickness of a piece of paperboard, carries an encrypted version of all the information needed to identify your wireless account to the network. You slip it into the appropriate slot on a GSM phone (usually under the battery) and that phone is ready to use.

Naturally, this means that you can use pretty much any compatible phone on a GSM network, with or without the carrier's permission. This is limited only by the phone supporting the right radio frequencies (850 and 1900 MHz for North America, 900 and 1800 MHz for overseas), and on the phone not being "locked" to a provider other than the one you're trying to use it with.

Not only can you use a wider variety of phones with your service, it also allows you to take any GSM hardware and make it "your phone" instantly, including the ability to carry your contacts right on the SIM card. You could literally take your phone, smash it with a hammer, extract the SIM card, and with a backup phone in your glove compartment be back up and running in 30 seconds. Or you could carry a pre-paid SIM with you and pop it into your phone in case there was ever a time when you wanted to have phone service but not be reachable by your usual number. GSM's strength is in its flexibility.

That's not to say CDMA providers don't have advantages. In the U.S., at least, Sprint and Verizon are well ahead of AT&T and T-Mobile on deploying high-speed Internet: both of the CDMA carriers have reasonably extensive wireless broadband footprints, while AT&T's is relatively small, and T-Mobile is still preparing to launch such a system. Thus, some users in the U.S. have to chose whether flexibility now is worth having to wait for the broadband coverage to catch up.

Answered by kishore at 1:52 PM on May 07, 2008

hi gaurav :-
GSM works throughout the world whereas CDMA only works in the US mostly and a few other countries. Verizon Wireless uses CDMA in the US and most of the other carriers use GSM. And not to reiterate what their slogan says, but they are the "most reliable network" so they're obviously doing something right here in the US.

Answered by shepherd at 1:51 PM on May 07, 2008

well, n cellular service there are two main competing network technologies: Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). Cellular carriers including Sprint PCS, Cingular Wireless, Verizon and T-Mobile use one or the other. Understanding the difference between GSM and CDMA will allow you to choose a carrier that uses the preferable network technology for your needs.

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.
CDMA phones are activated remotely, by the carrier, using the phone's serial number, known as the ESN. Since each carrier has a database of all the ESNs that are approved for its network, this lets most CDMA carriers refuse to activate phones not originally intended for their network.

GSM phones are activated differently. Each account is associated with what's called a SIM card, or Subscriber Identity Module. This card, about the size of a fingertip and the thickness of a piece of paperboard, carries an encrypted version of all the information needed to identify your wireless account to the network. You slip it into the appropriate slot on a GSM phone (usually under the battery) and that phone is ready to use.

Naturally, this means that you can use pretty much any compatible phone on a GSM network, with or without the carrier's permission. This is limited only by the phone supporting the right radio frequencies (850 and 1900 MHz for North America, 900 and 1800 MHz for overseas), and on the phone not being "locked" to a provider other than the one you're trying to use it with.

Not only can you use a wider variety of phones with your service, it also allows you to take any GSM hardware and make it "your phone" instantly, including the ability to carry your contacts right on the SIM card. You could literally take your phone, smash it with a hammer, extract the SIM card, and with a backup phone in your glove compartment be back up and running in 30 seconds. Or you could carry a pre-paid SIM with you and pop it into your phone in case there was ever a time when you wanted to have phone service but not be reachable by your usual number. GSM's strength is in its flexibility.

Answered by Saurabh at 1:49 PM on May 07, 2008

its quite simple buddy.. GSM mobile simply means a mobile where any network SIM can be inserted and can b used whereas CDMA mobile means a moblie with no SIM but runs under only one network .Hence in CDMA mobile phone u cannot even think of changing ur SIM..
so i prefer GSM is bettr.

Answered by prem sharma at 1:39 PM on May 07, 2008

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A mobile phone or cellular (cell) phone is an electronic telecommunications device.

A mobile phone is the type of cellular phone that is installed in a motor vehicle. There are three main types of cellular phones mobile, transportable, and portable. A mobile unit is attached to the vehicle, draws its power from the vehicles battery and has an external antenna.

A satellite phone or satphone is a mobile phone that communicates directly with orbiting satellites. Depending on the architecture of a particular system, coverage may include the entire planet, or only specific regions.

Answered by Mohd Farooq at 12:10 PM on May 07, 2008

Well Gaurav , GSM and CDMA differs in a big way.

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM.

CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world.

There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.

1) Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.

2) Data Transfer Speed: With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls.

CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies.

EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready.

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required.

In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance.

3) Subscriber Identity Module (SIM) cards: In the United States only GSM phones use SIM cards. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention.

The SIM itself is tied to the network, rather than the actual phone. Phones that are card-enabled can be used with any GSM carrier.

The CDMA equivalent, a R-UIM card, is only available in parts of Asia but remains on the horizon for the U.S. market. CDMA carriers in the U.S. require proprietary handsets that are linked to one carrier only and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one. The old phone becomes useless.

4) Roaming: For the most part, both networks have fairly concentrated coverage in major cities and along major highways.

GSM carriers, however, have roaming contracts with other GSM carriers, allowing wider coverage of more rural areas, generally speaking, often without roaming charges to the customer.

CDMA networks may not cover rural areas as well as GSM carriers, and though they may contract with GSM cells for roaming in more rural areas, the charge to the customer will generally be significantly higher.

5) International Roaming: If

Answered by Alok Gupta at 11:48 AM on May 07, 2008