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  1.    #1  
    I don't know much about GSM phones... except that Sprint and Verizon phones are CDMA and not GSM. My question is what make them so different?

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  2. #2  
    false premise. it isn't better. each have advantages.
  3. WyreNut's Avatar
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    #3  
    One plus - GSM phones have SIM cards in them, that enable you to change phones like shoes. If I want to use a different phone instead of my Pre Plus, I just yank the card and shove it in. Bang, I'm using my Centro again, or my old Sony w810i phone!

    Also, simultaneous data and voice is nice, along with the fact GSM is a worldwide standard.

    WyreNut
    Pre2/3/TouchPad, and TouchDroid user.
  4. #4  
    GSM is an acronym for Groupe Special Mobile, which has now been changed to Global System for Mobile Communication. CDMA refers to Code Division Multiple Access. The working of GSM and CDMA is very different. But the end result, after the implementation of the two technologies, is highly similar and matching in many ways. This article will try to highlight the subtle differences between the two technologies.

    GSM vs CDMA Technology

    GSM is a very straight forward standard, whereas, CDMA is somewhat complicated. The key difference between the two is that GSM is a standard and CDMA is a technology, but GSM has attained some technology status over the years. So, what is the difference between GSM and CDMA? Read on to find out.

    GSM Explained
    GSM is a 'cellular' technology, that is, the entire coverage area is divided into various hexagonal shaped cells (hence the popular name 'cell phones'). Every cell has a corresponding network tower, which serves the mobile phones in that cellular area. For example: Imagine a honeycomb on a tree in a hexagonal shaped garden. The garden has many flowers. The honeybees collect the nectar from the flowers, and deposit it in the honeycomb. Your mobile phones are like the flowers, the network tower is like honeycomb, and the bees are the signals.

    CDMA Explained
    As the name suggests (Code Division Multiple Access), there are many devices which use the same spread spectrum (hence multiple access). 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 (the codes may or may not change). For example: There is a street on which many buses ply. Obviously, the bus will have many commuters, and they will have to buy the tickets to travel on the bus. In CDMA, the commuter is like your mobile phone, the tickets are your codes, the bus is a multiplexed carrier signal, and the street is the spread spectrum.

    GSM vs CDMA Comparison

    Call Quality: This is an area where CDMA scores substantially over GSM. Statistics are hugely in favor of CDMA. Various factors such as echoes, call dropping, or voice distortion are almost non-existent in CDMA, whereas in GSM, there is a high probability of errors. To give you an analogy, the bus on the street will continue to ply even when it's full, but if the honeycomb has reached full capacity, the honey cannot be deposited.

    GSM vs CDMA Call Qality Score: CDMA scores. Goal count 0-1.

    Carriers: GSM is one up on CDMA as far as carriers are concerned. The law requires CDMA carriers to provide handsets to users, for which the users cannot change their carriers. Whereas, GSM users can change their carriers whenever they want.

    GSM vs CDMA Carriers Score: GSM scores. Goal count 1-1.

    Network: It's an on-going battle between the two. Both the technologies are continuously improving the qualities of their network and adding various aspects to it as well.

    GSM vs CDMA Network Score: Both score. Goal count 2-2.

    Worldwide: There is a special number that every GSM compatible device in the world can call in case of an emergency. That number is 112. But in CDMA, this cannot be implemented because of certain technological limitations.

    GSM vs CDMA Worldwide Score: GSM scores. Goal count 3-2

    Battery Life: GSM, being a relatively simpler technology, uses less amount of cell phone battery than CDMA.

    GSM vs CDMA Battery Life Score: GSM scores. Goal count 4-2

    Coverage: GSM and CDMA, both have similar network coverage areas. They are present almost everywhere. The service providers of both technologies are striving hard to cover whatever inches that are left.

    GSM vs CDMA Coverage Score: Both score. Goal count 5-3

    Speed: Both GSM and CDMA are rapidly improving their capabilities in this regard. Both have introduced 3G mobile phones in their fold. Both are competing to gain space in this area.

    GSM vs CDMA Speed Score: Both score. Goal count 6-4

    Building Penetration: Again, in initial days, both technologies couldn't find building penetration, but after research in signaling systems, and through experience, service providers of both technologies have been able to give decent service to the mobile phones in buildings.

    GSM vs CDMA Penetration Score: Both score. Goal count 7-5

    GSM vs CDMA: Which is Better?

    Both have their good qualities and bad qualities. GSM has some limitations where call quality is concerned, but GSM can be easily implemented and easily integrated into existing technology. Whereas, CDMA is little difficult to implement. By my estimation, GSM has an upper hand.

    More reading here http://www.howstuffworks.com/cell-phone.htm

    -- Sent from my Palm Pre using Forums Beta
  5. Helidos's Avatar
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    #5  
    Sketch did you seriously just post a wall of text from your pre? or did you copy paste?
  6. #6  
    Well I was going too... But was waiting for a bus.. So I ended up copy pasting


    Edit: the link at the end I typed
    -- Sent from my Palm Pre using Forums Beta
  7. #7  
    Another advantage CDMA has over GSM is even in a very low signal area a CDMA call will be clear, then cut out when the signal is lost. On GSM, when the signal is low it is very noticeable by hearing echoing, garbled speech and distortion. I can usually tell when I am talking to someone who is on a GSM phone by just listening to the call quality. It is very noticeable.
    Palm Vx -> Treo 600 -> Treo 700p -> Centro -> Pre (Launch Phone 06/06/09) -> AT&T Pre Plus with Sprint EVDO swap -> Samsung Epic 4G w/ Froyo
  8. #8  
    Quote Originally Posted by sketch42 View Post

    Call Quality: This is an area where CDMA scores substantially over GSM. Statistics are hugely in favor of CDMA. Various factors such as echoes, call dropping, or voice distortion are almost non-existent in CDMA, whereas in GSM, there is a high probability of errors. To give you an analogy, the bus on the street will continue to ply even when it's full, but if the honeycomb has reached full capacity, the honey cannot be deposited.

    GSM vs CDMA Call Qality Score: CDMA scores. Goal count 0-1.
    I have doubts about this one. Maybe it's just Bell's network, but I actually have more dropped calls due to "signal fading". Back on Fido with my 3-year old Nokia I never had one dropped call.

    So I think geography and carrier equipment has a very big factor in this.
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  9. #9  
    Also another thing... UMTS (i.e. "3G GSM") allows simultaneous voice and data. You can't do that with CDMA EV-DO. There was EV-DV which promises this, but it was never implemented by any carrier and there's no equipment for it.
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  10. #10  
    to add some extra confusion. UMTS is CDMA.
  11. #11  
    Quote Originally Posted by hagster View Post
    to add some extra confusion. UMTS is CDMA.
    Yes, I'm confused
  12. #12  
    Quote Originally Posted by GuyFromNam View Post
    CDMA does not allow sim voice and data?
    What if you want to look up the address of a restaurant while talking to the friend you're having dinner with?
    That is correct and it is one thing that I miss about GSM (besides the ability to move my sim card to different phones on a whim). If I'm talkin and need to look something up at the same time, CDMA phones come with a built in Prayer app that automatically starts and prays that I have a wifi signal nearby.
  13. #13  
    Quote Originally Posted by GuyFromNam View Post
    It's 2010 here. What year is it where Sprint is?

    No, but seriously. On GSM using both on a low signal means your call gets dropped 9 times out of 10 because the phone switches to G (at least, I think that's what it's doing).
    Yeah, I had AT&T for a few years of GSM service, but I dropped calls constantly (especially if I was driving and it switched towers). I lost some features moving to Sprint's CDMA service, but I rarely ever have an issue with dropping calls.
  14. #14  
    Surely calls get dropped at the same signal strength? GSM would just have lower quality in lower signal areas, but both would cut off at the same level. Call dropping then depends on the quality of your aerial and, more importantly, the signal quality from your carrier. In England we have multiple GSM carriers and it is well known that in some places (even as exact as one house), some networks have no/very low signal, while another network has full signal.
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  15. #15  
    Would be really nice if there was a way to switch CDMA phones between carriers like you can with GSM. That would give users a few more options.
    My device history:

    - Jim J.

    (On Sprint for many years)
  16. #16  
    Quote Originally Posted by jjeffcoat View Post
    Would be really nice if there was a way to switch CDMA phones between carriers like you can with GSM. That would give users a few more options.
    I have heard of people using their Verizon/Sprint CDMA phones on Metro PCS for example. Not sure how they are doing it. If Verizon and Sprint could come to some sort of agreement that would be great. If Sprint users could buy the Verizon Pre 2 and use it on Sprint that would be a big win.

    But updates would be an issue. I guess you would have to use webOS doctor each time there is an update, then tweak it for the Sprint network.
    Palm Vx -> Treo 600 -> Treo 700p -> Centro -> Pre (Launch Phone 06/06/09) -> AT&T Pre Plus with Sprint EVDO swap -> Samsung Epic 4G w/ Froyo
  17. #17  
    Quote Originally Posted by jonathan_twite View Post
    Surely calls get dropped at the same signal strength? GSM would just have lower quality in lower signal areas, but both would cut off at the same level. Call dropping then depends on the quality of your aerial and, more importantly, the signal quality from your carrier. In England we have multiple GSM carriers and it is well known that in some places (even as exact as one house), some networks have no/very low signal, while another network has full signal.
    there's a bits more to it than that. Most cdma often uses something called a rake receiver that adds all the reflected signal paths into one louder signal. This isn't possible on gsm.
  18. #18  
    The debate between GSM and CDMA can get pretty rabid. I've used both and prefer CDMA - but only because I've been a Sprint customer for a very long time and have gotten used to their network performance (and Verizon's, when roaming) where I live and work. When I had AT&T, I would frequently drop calls, and when I use my T-Mobile phone, I always have coverage problems. This isn't GSM's fault, but rather the carriers.' Still, I consider myself a "CDMA guy." I wonder how many people are the same.

    Interestingly, I have simultaneous voice/data capability on my Sprint phone (Evo) when I'm in a 4G coverage area. I have never had occasion to use it, because it's not something I care about. If you value that feature, GSM/UMTS is the way to go.
  19. #19  
    Quote Originally Posted by NickDG View Post
    I have heard of people using their Verizon/Sprint CDMA phones on Metro PCS for example. Not sure how they are doing it. If Verizon and Sprint could come to some sort of agreement that would be great. If Sprint users could buy the Verizon Pre 2 and use it on Sprint that would be a big win.

    But updates would be an issue. I guess you would have to use webOS doctor each time there is an update, then tweak it for the Sprint network.
    The no "SIM" limitation of CDMA is an artificial limitation. They could create CDMA devices that could run off a ROM card if they wanted to but there's no one that cares enough to force the issue especially since CDMA isn't a growing technology.

    What would be really nice would be if they could actually have overlapping signals. Devices that run on CDMA for the voice channel and GSM for the data channel. CDMA really does have superior call quality and stability over GSM. I believe it's probably because CDMA uses a dedicated signal for voice while GSM essentially uses a VoIP system over the data channel. There were experimental VoIP systems for EV-DO but no one has actually implemented them in real world so far and probably because of that quality/stability issue going over the data channel. Plus I don't think the bandwidth of EV-DO would handle it very well compared to 3G GSM, it's probably end up feeling more like EDGE.
  20. #20  
    Quote Originally Posted by hagster View Post
    to add some extra confusion. UMTS is CDMA.
    Wideband CDMA.

    The two "families" should be called IMT-2000 (i.e. CDMA) and GSM 3GPP.
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