Difference Between GSM and CDMA

The GSM logo is used to identify compatible ha...
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I think that having come from the cellular industry, I tend to forget that most people do not realize there’s an inherent difference between domestic carriers based on their technology types. And I was reminded of that when I read Jason Calacanis’ post on his case against Apple.

While I don’t agree with his perspective, I believe that the second point itself is made on incorrect assumptions and trying to give a case based on incorrect facts can lead to disaster. His second point in full is here:

2. Monopolistic practices in telecommunications
Apple’s iPhone is a revolutionary product that has devolved almost all of the progress made in cracking–wait for it–AT&T’s monoply in the ’70s and ’80s. We broke up the Bell Phone only to have it put back together by the iPhone. Telecommunications choice is gone for Apple users. If you buy an Apple and want to have a seemless experience with your iPhone, you must get in bed with AT&T, and as we like to say in the technology space, “AT&T is the suck.”

Simple solution and opportunity: Not only let the iPhone work on any carrier, but put *two* SIM card slots on the iPhone and let users set which applications use which services. (Your phone could be Verizon and your browser Sprint!) Imagine having two SIM cards with 3G that were able to bond together to perform superfast uploads and downloads to YouTube.

Now here’s the issue with this. CDMA carriers overall do not have sim cards in any way, shape or form. There are some Japanese phones that I have seen that were dual-radio and had modified sim cards for CDMA, but in general it doesn’t happen. The entire number is handled by the ESN which is coded to each phone. That’s the sixteen alphanumeric number that you give to your carrier when you “activate” your phone from behind the battery. The reason for this is that it’s basically two different radio technologies. GSM versus CDMA is much like the VHS versus Beta, or HD-DVD versus Blu-ray except both technologies exist together. But Jason’s want for a dual-radio phone is just not pliable not because it cannot be done, but because from a battery technology standpoint, we still haven’t reached a technological point where battery life is irrelevant.

GSM in itself is actually an older technology. It’s more widespread through Asia and Europe because of it, but the United States is dominated by CDMA (Qualcomm) because of the clearer voice quality and less likelihood of drop scenarios. Don’t let me fool you, CDMA will still drop because RF is a fickle animal, but the two technologies behave differently because of their own intricacies.

Why is this important to know? Well, there’s a difference between data evolutionary paths on both of these cellular technologies. For example, the 3G for CDMA is EVDO while the 3G for GSM is HSDPA. The entire method of choosing the right technology can effect your voice call quality. So for those that actually hate the dropped calls by AT&T because they happen too often? I can probably make the assumption without seeing the traffic patterns that it has a high likelihood of happening due to technology. But Apple’s choice of going with AT&T is very clear since the adoption rate would be towards the majority of market share on a global perspective.

Overall, understanding that there are differences between these two technologies can affect your judgment on which carrier you choose. By choice, I do not believe I would select a GSM carrier if based on voice quality and dropped calls along with the usual echo issues. But to each their own as far as what you’re willing to put up with at the time. Just make sure you understand that you can’t have sim cards with any domestic CDMA carrier.

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