Comment wise, one of the most popular posts here is about Cell Phone technology.  The comments have drifted in to cell phone protocols.

There are two main protocols, CDMA and GSM. CDMA is a legacy protocol only used here in the US. The rest of the world uses GSM.  This is an issue for hardware manufacturers, since the phone has to be built to support one or the other.

At least two of the major US carriers, Sprint and Verizon, still use CDMA.  So there still is a fairly large market for phones designed to use CDMA.

AT&T bit the bullet years back and coverted their network to GSM.  This probably gives them a slight advantage in pricing when buying phone in bulk from manufactures.  It also allows them to compete in the International market, since their phones will operate outside the CONUS.

Another advantage to GSM is the SIM card.  The part of the phone that identifies it to the network is designed to be an enduser replaceable device.  This makes the actual phone independent of the network (something that gives Verizon execs and Steve Jobs nightmares).

My iPhone, and my previous phone are both GSM devices, so I was able to take then SIM from my iPhone (Apple bricked it for about 12 hours) and put in my RAZR phone.  You can’t do that with a CDMA device.

Just from a technical, networking engineer viewpoint, my vote goes for GSM.


7 Responses

  1. I came across this article, which shows that the big 3 are in a virtual dead heat for market share, with a slight edge going to AT&T. It also shows that between Sprint and Verizon, half the cellphones in America are CDMA. My suspicion as to why they still do it, I think it comes down to money – neither Sprint nor Verizon will hook up a phone that they haven’t sold originally. What that means is they’re making a tidy profit on not just the cell service, but on the phones as well, because their customers are being forced to buy through them.

    Something you might have missed about GSM – it comes in multiple flavors – 850, 900,1900, 3G, etc. Just because you have a GSM phone, and your going to a GSM service provider, doesn’t mean that they’re compatible…

  2. Ok, so you are backing up some of my original claims on the topic, including Verizon’s addiction to the hardware sales revenue. AT&T (and Apple) do the same thing, but it is easier to get around. I can buy the cheapest GSM phone AT&T sells and put the SIM in another unlocked GSM phone. AT&T may not like that, but at least they are getting the service fee.

    Which is probably how other carriers view unlocked iPhones on their networks.

    CDMA allows Verizon and Sprint to lock hardware to their network. I prefer the UK model, where you buy a plan and SIM card from the network provider. What phone you put it in is your business.

    I haven’t had any compatibility issues with GSM phones yet. I’ve moved SIM cards between several different types of phone with no problem. My wife’s 3G GSM based phone works fine on the same network my non 3G GSM based phone does (better actually, since we have 3G coverage here), and she had no problems with her old GSM phone during her travels in Europe a couple of months ago (four countries, working signal in all of them).

    Overall, I’ll give a US sold GSM phone a lot better chance of working in Munich than a US sold CDMA phone.

  3. Yeah, there are a couple of different GSM networks — the system used in the US uses a frequency which can make speakers sound funny. But it’s common for GSM phones to work on more than one network.

    When I was living in Paris I bought a Treo 650 in Boston, used it in France with my Orange SIM, and upon returning to the US used the same Treo with AT&T. Orange didn’t roam to the US, unfortunately.

  4. Not exactly – you claimed it was because they wanted control. I don’t see it exactly like that – more like another way to squeeze money out of customers. If they couldn’t get the additional revenue stream, I’d doubt they’d care.

  5. I didn’t imply that Verizon wanted control over the devices because their CEO has a monocle and a white Persian cat.

    It’s because they want to force you to only access the phone over their network. The don’t do that because the Chairman of the Board and his roommate Pinky are planning on taking over the world.

    It is so they can force you pay high prices for a snippet of a song to use as a ringtone.

    The control of the network is *all* about the money.

  6. Some companies are about control, simply because they want it cough, Apple, cough..

    The whole “force the client to do what you want to squeeze more money out of them” is pretty standard business practice for pretty much every company out there, at least for the ones who can get away with it. Hell, MAKE came out with the slogan “If you can’t open it, you don’t own it”.

  7. […] pushing its much wider 3G coverage heavily, but it’s still not a GSM network.  That topic has been discussed here, and I’m sure it will again, but I’m still a fan of GSM networks.  It is my opinion […]

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