GSM Vs. CDMA: What Is The Difference And Which Is Better?

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Most cell phone owners around the world only have to worry about a single carrier technology called the Global System for Mobile Communications, or GSM for short. As its name implies, this standard was developed for, and has been adopted by, almost the entire globe as the way to communicate via cellular calls.

But¬†not everyone has jumped on the GSM train. An alternative cellular standard known as Code Division Multiple Access, or CDMA, is used by many carriers around the world. It is most popular in the United States and Russia, but it’s also used in some¬†Asian and African countries, often alongside competing GSM carriers.

Here’s what cell phone users stuck on choosing between them should know before purchasing a phone.

GSM vs. CDMA: What’s Better?


This the first question many potential owners ask, and it makes sense, but in this case there’s no easy answer to that question.

GSM and CDMA are different ways to accomplish the same goal, and the fact that extremely popular networks are built on each simply proves that it’s the quality of the network, not the standard, which is important. For instance, in the United States, two of the four major carriers (Verizon and Sprint) use CDMA while the other two (AT&T and T-Mobile) use GSM.

Technically, neither is the better in terms of quality, but there are some things here for your consideration. GSM phones are able to be unlocked and moved between carriers, but CDMA phones are often locked to a single carrier and unable to be transferred.

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Additionally, most phones only come in GSM or CDMA models, so your choice of phone could determine which standard you end up using, and it all depends on which carriers are available to you in your area. Some areas may be better covered by GSM-providers, while CDMA-providers will have better coverage in other areas.

What Phones Support Which?

Many¬†phones are compatible with¬†either¬†GSM or CDMA, but not both. For CDMA phones, you will need to buy a phone made for your specific carrier, and the easiest way to do this is buy directly from your carrier. For example, if you want an iPhone on Verizon, you need to buy a Verizon-branded iPhone — not a Sprint- or AT&T-branded iPhone — because it has the specific bands and compatibility with Verizon. However, if you ever want to leave Verizon, you won’t be able to take your phone with you; it is locked to that carrier.


If you don’t want to be trapped with one carrier, however, you can also look for unlocked GSM phones from third-party retailers — these phones will work with any GSM carrier simply by popping in your SIM card.¬†For example, Amazon sells tons of unlocked GSM phones, and Google sells their Nexus 5 and a couple Google Play Edition phones unlocked. Any retail or online store dealing in cellular phones should provide information regarding the networks a phone works with.

You must be careful when examining a phone’s network compatibility, though. Phones sold in markets that service both standards¬†often come in a GSM version¬†or¬†a CDMA version, but only a few phones are compatible with both. If you buy a CDMA phone from a third-party retailer, you’ll need to call your carrier to have it activated. If you buy a GSM phone, you’ll need to purchase a SIM card to put into your phone that will activate your phone’s network capabilities.


Owners of CDMA phones don’t need to worry about SIM cards, but¬†this is more a curse than a blessing. CDMA phones bake¬†in compatibility restrictions that are difficult to get around, while GSM owners can simply take out their SIM and replace it with one from another carrier. Most¬†CDMA networks do not allow the use of a phone originally purchased from another carrier even if the phone is otherwise technically compatible. This is an important restriction to remember when going with a CDMA network. If you decide to switch networks later you’ll likely need to buy a new phone even if the network you’re switching to also uses CDMA.

While GSM is more open, the frequency bands supported by a phone can still restrict access.¬†There’s a number of bands from 380 MHz to 1900¬†MHz¬†and the bands used can vary¬†from market to market. You should double-check your local carrier’s band usage and make sure the phone you’re buying supports the same. ¬†With that said, GSM is concentrated around a core of four bands, those being 850, 900, 1800 and 1900. A phone that supports all four can be used in most countries, which is why GSM phones compatible with all four bands¬†are often called a “world phone.”

LTE Cometh, And Carries Confusion

If you now understand the importance of GSM and CDMA, awesome! Now let’s entirely destroy your assumptions by talking about the newcomer,¬†Long Term Evolution (LTE).

LTE is a new standard that’s come into vogue over the last few years. Though based on the principles of GSM, LTE is its own separate standard that operates apart¬†from existing GSM and CDMA networks — it’s the real fourth generation of cellular data.


The¬†highest adoption of LTE can be found in¬†South Korea, where it commands the majority of the market, but it is also popular in Japan, Australia, Sweden, and the United States.¬†So far it’s used primarily for data, but standards have been drawn up for using LTE as a replacement to traditional cellular networks. Verizon Wireless in the US, for example, has announced its plan to roll out LTE-only phones in late 2014.

This standard uses a SIM card, so users can switch networks by replacing the SIM if the phone is compatible with the new network. With that said, at this time phones that use LTE generally use it only for data, but not for voice. This means CDMA/LTE phone owners are still locked into a network. That will change as carriers like Verizon move to LTE-only networks, but this process could take many years.

While it has the potential to be a global standard, there are some obstacles in the way.¬†Outside of South Korea there’s no market where LTE’s reach is more than a quarter of the services¬†available. South Korea in general, and Verizon Wireless in the US, are exceptions to the rule; in most markets, even carriers that offer LTE only offer it in a slim selection of the total area¬†they cover.


And then there’s the problem of spectrum. Remember how GSM/CDMA¬†operates on many different bands? The same is true of LTE. You need to check that the compatibility of your phone matches the frequency band supported by your carrier, and you won’t be able to use an LTE phone on other networks with the same standard, but a different frequency band. It’s unclear at this point if this standard will ever become “global” in the same way as GSM, which settled on a core of four frequencies across the world that are supported by most GSM phones.

Wrapping It Up

Take a deep breath; it’s time to review this buffet of confusing information.

First, neither GSM or CDMA is technically better; they ultimately provide the same service and the quality of a network depends on the carrier, not the cellular standard used.

Second, GSM phones can be unlocked and switch carriers, whereas CDMA phones are locked to a carrier. It’s usually cheaper to buy unlocked GSM phones than on-contract CDMA phones.

Third, you need to check what bands your chosen phone supports carefully. Most either work on GSM or CDMA, and both standards offer multiple frequencies that differ across the globe.

Finally, LTE is being rolled out as a potential global standard, but it¬†falls victim to even more¬†frequency division than GSM and CDMA. The technology also suffers from limited adoption because it’s relatively new.

Hopefully this has cleared up any questions you had, but cellular service is undergoing constant evolution and the standards commonly supported by phones can change from year to year. Feel free to leave your questions and comments below.

Image Credit: Wikimedia/Jon Ravi,¬†Man’s hand holding black GSM SIM card and Good looking guy on a cell phone¬†from Shutterstock.

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34 Comments - Write a Comment


Ant Man

Due to FCC spectrum agreements, Verizon is required to not lock their LTE phones.

i.e. iPhone 5S, and 5C are compatible with AT&T, T-Mobile and Verizon.

John Dugue

True, but verizon is being slow to allow this, the last I knew.


Tom W

I’ve used both a HTC Sensation and a Samsung Galaxy S3. Both of them allow switching between GSM, which is better for voice and text signal, and WCDMA, which is better for mobile data speeds. I don’t know whether it is because I live in the UK, or if I just got lucky with the phones I bought.

Arun S

WCDMA is different from CDMA WCDMA actually refers to 3g and GSM refers to 2g in the context u r talking as far as indian technology is concerned

Tom W

That makes sense, thanks. It’s annoying that they use two confusingly similar acronyms to mean different things.



Some CDMA phones can swap “SIM” cards too, but they are called R-UIM (Removable user identity module), which is the old standard, and CSIM (CDMA Subscriber identity module), the new standard, instead of SIM (Subscriber identity module).



Lucky for us here in Indonesia, each GSM found are sold unlocked, even if you buy it from carrier (off-contract). As for CDMA carriers here, currently are 2 but by the end of 2015 CDMA will be totally dead here as carriers are forced to use GSM/LTE 2600 Mhz


Greg Iles

You left out the biggest deficiency of CDMA vs. GSM, that is, that you cannot use your phone and data at the same time on CDMA. IF you are browsing, foe example, and the phone rings, you are cut off from the internet if you answer and cannot get back on until you hang up. TO me, CDMA has absolutely no advantage over GSM.

david bartlett

From a carrier standpoint it means more capacity. More devices on the same channel. Where on GSM you can only have one device on each channel.



Looking at the heading of the article, I was excited I would get to know the difference between CDMA and GSM. But to my my disappointment the whole article revolves around just the pros and cons. No difference highlighted. Poor construction.


CDMA uses code to mux (multiplex) a voice signal into a dedicated data path containing multiple voice signals. GSM uses TDM, or time division multiplexing which assigns a call to one channel in the bit stream, similar to a T1 (DS1).


Robert B

Hey Matt, you said that LTE is the real fourth generation of cellular data, but primarily mentioned GSM and CDMA… What is the missing fourth? Just curious



The missing fourth is 3G, which are WCDMA and UMTS technologies. Please search Wikipedia for more info about 2G, 3G and 4G, since they are nit necessarily easy to explain.



Actually 4G is defined by data rates and other two-way spectrum comms protocols: 1 GB stationary DTR and 100 MB mobile. The FCC caved to vendor pressure to redesignate current (LTE) data rates as “4G” for marketing purposes. Wimps.



GSM iPhones could do Data and Voice SIMULTANEOUSLY, CDMA can not so, if you’re on a Voice call on your Verizon or Sprint iPhone and need to check Data, you must first end the Voice call. With a GSM based iPhone, the Voice call can continue while you access the online Data you need. I thought the when Verizon adopted 4G/LTE, Verizon would gain this capability. I’m told by Verizon reps that it is not the case. Even on a 4G/LTE Verizon phone, you still can do Voice OR Data but NOT BOTH TOGETHER.


Unless you’re connected to a wifi then you are able to do voice and data simultaneously.


On Verizon, simultaneous voice and data is supported. Sprint, however, drops to 1x during voice call, so the network doesn’t support voice and data simultaneously.


Melano S

You must be careful when examining a phone’s network compatibility, though. Phones sold in markets that service both standards often come in a GSM version or a CDMA version, but only a few phones are compatible with both. If you buy a CDMA phone from a third-party retailer, you’ll need to call your carrier to have it activated. If you buy a GSM phone, you’ll need to purchase a SIM card to put into your phone that will activate your phone’s network capabilities. Good post. I need it


Not true. I have Verizon. I can talk and surf the Web all at the same time. I have a Motorola RAZR Maxx and Note 4. None have issues .



Does one network over the other put a drain on your battery? Or am in left about this? :)



OK, I have a Samsung Galaxy mini that someone brought from South America and it takes a sim card, Can I take my sim card from my tracfone and use it in the galaxy?


no sim cards are locked to a particular phone once the phone is turned on first time. have to get new sim card for different phone


I’ve moved sim cards between phones without having to do anything else. It just has to be a phone set up for the same carrier.


Lionel Lombendencio

Great info I’ll just go with the GSM. Honestly here in our country we don’t have HDMA phones here SIM card is rampant where we have dual SIM phones. He he he he


pat jones

I just bought a zte valet from TracFone for $29. From what I understand it operates in Verizon’s CDMA network which covers most of the Unted States excluding Alaska and some rural areas. Coverage is better than my old T-mobile flip phone that only operates on 1900 MHz; it doesn’t even roam onto at&t’s network in the countryside.



GSM is better. Someone needed to say it.



After reading your article, I was wondering if I could buy an iphone 5s with a AT&T contract, and then use it overseas with another sim-card when I need to.


Susan D

Thanks for the great write-up!
I’m trying to decide if I should switch from my Sprint iPhone5 to t-mobile… and if I do, which phone would be best for USA coverage and frequent 3rd world travel. :-/
Any suggestions? I mostly use data, in the states and abroad.



my cdma operator starts charging when the phone starts ringing, but not when the other party answers


Eugene Ochieng

Thank you so much for the information



Thank you.



i get a phone lgvol that from USA cdma version of sprint.can i work this cdma phone by using a indiannetworkprovider.


Gary Lasereyes

Great Article thanks!



I live in Arizona. I have a couple of questions. First, I have a Samsung Galaxy S4. It’s both cdma and gsm. I’m switching it over to straight talk. What does Verizon towers use, cdma or gsm? Also, I’ll be in Alaska for a couple of months and I saw they don’t support cdma. If I go with cdma will I still be able to use the phone while I’m in Alaska?

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