Which system is better GSM or CDMA? And why did CDMA stop to use, to upgrade?

Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA) are two competing standards in cellular service. They both have derivatives for use with3G phones known as Universal Mobile Telecommunications System (UMTS) and CDMA2000, respectively. The major difference between the two technologies is how they turn voice data into radio waves and how the carrier connects to the phone. Other differences include the coverage area, the data transfer speeds, and the type of hardware used. Coverage Some areas and countries only have one technology available, so users should be sure to review coverage maps before buying a phone. Generally speaking, CDMA is most commonly found in North America and some parts of Asia, while GSM is found in most other places. Some carriers do offer international or "world" phones that can work with both, but if the phone is going to be used predominantly in one area, it may make sense just to get one that's tied to one type. Data Transfer Speed Both technologies can be used with3G standard phones, but3G GSM speeds can be faster than3G CDMA speeds, which can make a big difference for those who use their phones for social networking, email and streaming video. The fastest3G standard used with CDMA2000 is EV-DO Rev B., which has downstream data rates of about15.67 Megabits per second (Mbit/s). The fastest standard available with UMTS is HSPA+, with downstream speeds of up to28 Mbit/s. Hardware GSM phones and CDMA phones also use different types of smart cards known as Universal Integrated Circuit Cards (UICC). These are small removable cards that can be used to store information like a contact list and activate, interchange, and upgrade phones without carrier intervention as long as the phone is unlocked. This means that the carrier makes it possible for phone to work even if the end user removes and changes the card. Though both types can be sold locked, this is more common with CDMA phones. UICCs can be programmed to work with either GSM or CDMA and their derivatives, or with both. Those that only work with GSM phones are called Subscriber Identity Module (SIM) cards and those that only work with CDMA phones are called CDMA2000 Subscriber Identity Module (CSIM) cards. There are also a few types of UICCs that are programmed to work with GSM, UMTS, CDMA, and CDMA2000, including CSIM/USIM cards and Removable User Identity Module (R-UIM) cards.

GSM and CDMA are two different standards with different functionalities and radio access technologies. It cannot be decided which is better. GSM provides much better coverage and voice quality with less complicity than CDMA. However, CDMA provides higher capacity and, of course, much higher data rates, where the GSM was not intended for data services.

CDMA method was mostly replaced by the WCDMA, which uses wider bandwidth (5MHz) to reduce the interference in the shared carrier.

GSM is better as it is globally accepted and used except some countries.You can change the sim cards whenever you like and you put that in any other phone you like. For data transfers it offers networks like GPRS, EDGE, and the latest HSDPA [3g] Technologies.

In CDMA network,there is one physical channel and a special code for every device in the coverage network. Using this code, the signal of the device is multiplexed, and the same physical channel is used to send the signal.In GSM network,every cell has a corresponding network tower, which serves the mobile phones in that cellular area.International roaming accessible is less in CDMA and more in GSM.Handset network service is specific in CDMA ,but in GSM it is SIM specific, The GSM phone is suitable for the roming by the switching capacity of networks.User has option to select handset of his choice ,sometime it will locked with a particular network contract for a particular periods, but we can remove it by getting the unlocking service from an provider like Mobile-Unlocker.com .But in CDMA we can't swith the mobile to another network  .

Migration path for technologies is quite an important factor. GSM, WCDMA, LTE and LTE-A provides a clear migration path. 

Thank you very much for your question.

GSM - Global system for mobile communication, consist of different kind of mobile communication networks and systems hncluding mobile satellite communication networks and systems (even GPS - Clobal positioning systems) to cover the clob - all over the world.

- CDMA ( code division Multiple Access- one of the sharing modes of communication channel -Muliple access. There are FDMA, TDMA, PDMA, and CDMA.

CDMA consist of too much different codes, and in current time this mode is most important mode and upgraded very fast. In near future we will see WCDMA ( Wave length CDMA).

CDMA is similar to many people in one room speaking all together but in different languages

Best regard       

Gsm is the most useful in our world now but the technology cdma is better in communication because communication by code is save and less of noise then tdma that use in gsm 

The CDMA is more comfortable which mean is good system but other disadvantage of the system its high cost more and used in country more wide like United State of Amirca.

CDMA provides higher capacity and much higher data rates, where the GSM was not intended for data services

CDMA is better than GSM as inference in CDMA is very less and also more capacity.