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  • [Prototype]

    Member • Sep 1, 2012

    GSM & CDMA are two different technologies. They both works on different frequency spectrum. CDMA comes under the category of 'Spread Spectrum' modulation technology & hence is more secure type of communication but consumes more bandwidth.

    The difference is certainly not in sim card, but the mobile hardware which use these technologies.
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  • Abhishek Rawal

    Member • Sep 1, 2012

    First of all, there is no such thing like "CDMA sim ", CDMA devices & GSM devices are available in market.
    One important feature difference between CDMA & GSM is SIM.
    In CDMA device, No SIM is there. While in GSM, SIM slot is available.
    The main advantage of CDMA over GSM is that, the operators gives the service to store the user data. So, by there is no problem while changing the handset, backing up all contacts are pretty easy.
    Main advantage of GSM is that you can switch SIM frequently without any hassle. Also, GSM devices can be used in foreign countries, just swapping SIM will do the job.

    Coming to data transfer, EVDO (also known as CDMA2000) gives downlink speed of 2 MBps, but real world speed is closer to 500-700 KBps; which available only for CDMA users.
    GSM's answer is GPRS (it's pretty slow than EVDO), the latest update to GPRS is EDGE, giving downlink speed of 384 KBps (theoretical)

    In CDMA device, each of the device has a physical layer in the coverage network. Using the code in physical layer the multiplexing of device is done & same physical layer is used in sending the signal.
    While in GSM, Every "cell" (here,cell doesn't mean cell-phone) has corresponding network tower, which serves mobile phones of that specific network area.

    In India, Airtel, Aircel, BSNL, Vodafone are on GSM , while Reliance & Tata telecomm are on CDMA networks. US is only country where CDMA has dominated mobile devices. While rest of world uses GSM service.
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  • pikachu1994

    Member • Sep 1, 2012

    oh,ok.thanks both of you.😀
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  • dayamayee

    Member • Sep 3, 2012

    u said that 'In CDMA device, No SIM is there.'if there is no sim or no slot for sim in CDMA device,then how that phone works?please rply
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  • [Prototype]

    Member • Sep 3, 2012

    dayamayee
    u said that 'In CDMA device, No SIM is there.'if there is no sim or no slot for sim in CDMA device,then how that phone works?please rply
    CDMA phones may or may not have sim cards. A phone without sim is generally built to serve only one network. For eg. If you buy a phone from Reliance, you can never use it with any other CDMA services. The required information which sim provides explicitly is already embedded on the phone's hardware in case of simless phones.

    The phones were simless at the start, but after sometimes, sims are allotted with CDMA phones as well so that you can switch between networks without changing the phone.

    The difference between CDMA & GSM doesn't lie if there's a sim or not. They are both different technologies, occupy different frequencies on the spectrum and employs different modulation & distribution techniques. That's the difference.
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  • Kaustubh Katdare

    Administrator • Sep 3, 2012

    Umm, quite a basic question it is. Right? I think the discussion would be interesting if we get into specifics of the differences.

    pikachu1994
    What is the difference between GSM and CDMA SIM card?
    Have you tried to list out the differences on your own?
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  • pikachu1994

    Member • Sep 3, 2012

    No,i don't have any idea.
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  • pikachu1994

    Member • Sep 3, 2012

    I know this alone.
    GSM-Global system for Mobile Communication
    CDMA-Code Division Multiple Access
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  • Kaustubh Katdare

    Administrator • Sep 3, 2012

    pikachu1994
    I know this alone.
    GSM-Global system for Mobile Communication
    CDMA-Code Division Multiple Access
    How about finding out some more information about this online? You'll then be able to ask very specific questions?
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  • pikachu1994

    Member • Sep 3, 2012

    Yeah,you are right.I"ll come back to you after studying that.😀
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  • ashie

    Member • Sep 3, 2012

    One thing i learn in cdma...i want 2 share with u all::😳

    CDMA uses a digital modulation called spread spectrum which spreads the voice data over a very wide channel in no recognizable patterns using a user or cell specific random code. The receiver undoes the randomization to collect the bits together and produce the original data. As the codes are unrecognizable and selected in such a way as to cause minimal interference to one another, multiple users can talk at the same time and multiple cells can share the same frequency. This causes an added signal noise forcing all users to use more power, which in exchange decreases cell range and battery life.
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  • dayamayee

    Member • Sep 5, 2012

    SIM-subscriber identity module
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