Android iPhone and iPad Technology Explained

GSM Vs. CDMA: What Is the Difference and Which Is Better?

Matt Smith 21-08-2014

Updated by Gavin Phillips on 05/30/2017


Most cell phone owners around the world only have to worry about a single carrier technology. It’s 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. However, 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. 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 Is It Legal Or Illegal To Unlock My Smartphone In The US? Unlocking your cellphone is now legal in the United States thanks to a bipartisan bill signed into law by President Obama, but it only lasts until 2015. Care to learn more about the legality of... Read More and moved between carriers, but CDMA phones are often locked to a single carrier and unable to be transferred.

Additionally, most phones only come in GSM or CDMA models, so your choice of phone could determine which standard you end up using. 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. (Rubbish cell-coverage? Here’s some effective ways to boost your signal! 8 Effective Ways to Boost Your Cellphone Signal If you're ever in a position where you aren't getting enough reception, here are some tips you can use -- some easy, some not so easy -- to boost your signal. Read More )

Which 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. The easiest way to do this is buy directly from your carrier Never Buy a Phone From Your Carrier! Buy Unlocked Phones and Save Hundreds Unlocked phones can cost a fortune, but the savings more than make up for it. You can save thousands by not signing a contract. We've got six phones that come contract free! Read More . 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 How To Save Hundreds On Your Mobile Phone Bill In 3 Easy Steps Cutting your mobile phone bill in half takes only three simple steps - first, find a carrier that offers discounted plans, such as an MVNO. Second, get an unlocked phone. Third, and optionally, you can... Read More , 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 What Is a SIM Card and What Does It Do? What is a SIM card and why is it so important? It connects you to your carrier network, stores contact information, and more. Read More . For example, Amazon sells tons of unlocked GSM phones, while Google sells their Nexus 5, Pixel, and a couple of Google Play Edition Love the Nexus but Don't Want a Pixel? Here Are Your Options If you loved the Google Nexus line but are disappointed with the announcement of the Google Pixel phone, this guide will help you find the perfect phone for you. Read More phones unlocked. Any retail or online store dealing in cellular phones should provide information regarding the networks a phone works with.

Google Pixel XL 128GB Unlocked GSM Phone w/ 12.3MP Camera - Quite Black Google Pixel XL 128GB Unlocked GSM Phone w/ 12.3MP Camera - Quite Black Buy Now On Amazon $133.94

Check Compatibility

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 Never Buy a Phone From Your Carrier! Buy Unlocked Phones and Save Hundreds Unlocked phones can cost a fortune, but the savings more than make up for it. You can save thousands by not signing a contract. We've got six phones that come contract free! Read More .

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) EDGE, 3G, H+, Etc: What Are All These Mobile Networks? Are you on the fastest mobile network? If not, where do you fall on the spectrum? These mobile network symbols can be confusing, but don't worry because we'll clear it up for you. Read More .


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. However, 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.

Global Adoption

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. 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.

And before you know it, the next global communication standard — 5G — will be upon us. See our comparison of 4G LTE and 5G LTE vs. 4G vs. 5G: What's the Difference? Should your next phone be LTE or 4G? Maybe 5G? Learn which mobile broadband is fastest and compare LTE. vs 4G. vs 5G. Read More for more info.

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 global standard. Unfortunately, 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. Cellular services are undergoing constant evolution and the standards commonly supported by phones can change from year to year.

For more, check out how to unlock your phone with free unlock phone codes How to Unlock Your Phone Using Free Unlock Phone Codes Here's where you can find free phone unlock codes to unlock your phone and switch to another carrier. Read More .

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

Related topics: Android, iOS.

Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.

Whatsapp Pinterest

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. Hector J Fontanez
    June 13, 2019 at 3:54 pm

    The basic conclusion of this article is not technically true. Due to properties inherent to the type of modulation used to carry cellular signals, CDMA is more susceptible to signal degradation when going through walls and other type of barriers. This article failed to go into these types of differences in technologies.

    It also failed to explain how the technologies handle things like number of users per channel and so forth. These differences are unknown to users and do affect quality of service even if ever so slightly.

  2. mike
    March 12, 2019 at 12:49 am

    ok. So what pray tell it's the difference in cdma and wcdma.

  3. Mike
    July 29, 2018 at 1:25 pm

    Uhhh..... no, your not locked to the carrier permanently when you have a CDMA phone. Fix that info and stop confusing people.

  4. Emma
    January 5, 2018 at 12:42 am

    Hi, thanks for the information, I found it very useful, but still have further questions. I am about to buy an unlocked iphone 6s from a 3rd party retailer in Australia. The intention is to take it overseas, firstly to Europe and then Canada. I am not too concerned about it working in Europe, but it needs to function as a normal phone in Canada as I will be living there (voice/text/data). I have done a lot of reading and am 90% sure that the iphone 6s is compatible with a lot of frequencies and carriers in Canada, but is there any way I can find out for sure? Would it be worth going to speak with someone from Apple? Thanks so much.

    • Paige Winona
      January 10, 2019 at 1:41 am

      Hi there!

      You can enter (if where your buying the phone from provides the phones IMEID/MEID) into your potential carriers coverage map. This will determine in Canada which network would have the best coverage for you, in regards to the location of your home! It will show you how good the connection will be in relation to your location and its towers.

    October 8, 2017 at 1:02 am


    • Mike
      July 29, 2018 at 1:29 pm

      Yes, as long as your Verizon CDMA phone has been approved for a domestic unlock from verizon. Call Verizon and get accounting services on the phone and ask for a domestic unlock. I’ve done it 10 times or more for friends and myself.

  6. April Kroll
    September 8, 2017 at 3:37 pm

    Question: Where I live, there's no GSM coverage. Since LTE only covers data, does that mean I still I'm stuck with the CDMA carriers/phones even with "LTE phones?"

    August 15, 2017 at 5:19 am

    HELLOO. I AM ON METRO PCS WITH A ZTE PHONE is unlock is a GSM / HSPA / LTE . i drive trucks and i need to change to verizon . if a get a GSM PHONE to verizon i will have the same signal en all places as a phone with CDMA. OR I MAY have les coverage. this is because verizon is a CDMA. THANKS.

  8. marc
    May 17, 2017 at 10:28 pm

    Excellent summary, much thanks! This is a clear and unbiased overview, exactly what I was looking for.
    Nice work.

  9. Gerald lowman
    January 16, 2017 at 4:23 am

    Can I still use my Sony Xperia GSM phone if I even own a bill on it and can I get it unlocked

  10. Chandan gupta
    January 15, 2017 at 2:37 pm

    what are the specifications for the lte technology launched by reliance jio . what is volte and lte as i have seen that if phone supports volte than even if data connection is off we can make the call and in lte if data connection is off than we neet on it and then make the call.
    Is it gsm/lte of cdma/lte ?

  11. Eliot
    November 19, 2016 at 5:14 am

    No comment but a question. I ordered a iPhone 6s , unlocked so I could get a GSM Sims card and activate it with at&t service. Was I supposed to tell Apple that I needed a GSM type iPhone or am I OK ?

  12. Shabbir Sh.T. Shakir
    August 1, 2016 at 10:59 am

    thanks for the info, but technically which is better?

  13. Christa
    January 21, 2016 at 8:58 pm

    The biggest difference I see between GSM and CDMA phones is that the FIRST troubleshooting step for a GSM is to remove and reinstall the SIM card. This was something I did on my Huawei and Blu phones many times, without a failure.

    However, not all phones have such robust SIM slots.

    I have tried to load the Consumer Cellular SIM into new MOTO G 3rd Gen phones and 3/4 of the time had to replace the phone. Consumer Cellular uses a compound SIM (Their nanoSim is inside a frame to make it microSim size, and a Standard SIM frame is around all of that.

    Twice the microSim card broke on insertion, leaving shards of plastic from the microSIM frame inside the SIM slot. On another attempt, the microSIM separated from the Standard Sim frame neatly and easily enough, but broke off a gold contact on insertion.

    I don't know whether Motorola considers Consumer Cellular's compound SIM system to be
    "use of an adapter" which would violate Motorola's warranty.

    I understand that adapters vary in quality, and surely understand why Motorola wouldn't warranty a phone with a homemade adapter. On the other hand, without an adapter to provide a smoother surface, I fear that it's a very risky proposition to plan on routine re-installation of a Consumer Cellular SIM into a MotoG phone.

    Otherwise, we love the Moto G III. We're living on Social Security and can't afford $500 phones. We have loved and recommended Consumer Cellular for their customer service and low cost (we were spending $38/mo altogether for 2 phones.) However, I can't figure out how we can use both because of this problem with the SIM cards.

    Any suggestions? After talking with both companies (which blame each other), we're getting desperate.

  14. Lin
    January 12, 2016 at 4:30 am

    How does straight talk fit into this?

  15. kona sam
    December 18, 2015 at 2:03 pm

    CDMA phones also come with sim card. Infact CDMA phones without sim card are extinct now.

  16. Anonymous
    October 21, 2015 at 6:49 am

    , 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. so how this GSM &CDMA are work!!!!!!!!!!!!!!!!!!!111

  17. Anonymous
    June 18, 2015 at 10:36 pm

    Good stuff

  18. Daudi Steve
    May 26, 2015 at 4:03 pm

    Quality Article

  19. Robert
    March 31, 2015 at 7:33 pm

    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?

    • Garland
      May 22, 2015 at 5:00 pm

      @Robert: Verizon uses CDMA.

  20. Gary Lasereyes
    March 20, 2015 at 3:32 pm

    Great Article thanks!

  21. deepu
    February 12, 2015 at 10:40 am

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

  22. Saimum
    February 8, 2015 at 6:52 pm

    Thank you.

  23. Eugene Ochieng
    January 23, 2015 at 6:08 pm

    Thank you so much for the information

  24. tino
    January 21, 2015 at 8:48 am

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

  25. Susan D
    January 15, 2015 at 9:36 am

    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.

  26. BrokeMyPhone
    January 14, 2015 at 7:34 pm

    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.

  27. Jay
    December 21, 2014 at 12:19 am

    GSM is better. Someone needed to say it.

  28. pat jones
    December 21, 2014 at 12:01 am

    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.

  29. Lionel Lombendencio
    December 7, 2014 at 6:25 pm

    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

  30. Richard
    December 3, 2014 at 2:47 am

    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?

    • happyhal
      March 6, 2015 at 2:54 pm

      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

    • Richard
      March 19, 2015 at 8:23 am

      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.

  31. Gene
    December 1, 2014 at 6:17 pm

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

  32. Moe
    November 2, 2014 at 7:50 am

    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 .

  33. John
    August 22, 2014 at 11:31 pm

    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.

    • Anonymous
      August 23, 2014 at 12:25 pm

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

    • Anonymous
      August 23, 2014 at 1:26 pm

      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.

  34. LB
    August 22, 2014 at 11:07 pm

    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.

  35. Hirst
    August 22, 2014 at 9:20 pm

    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.

  36. Robert B
    August 22, 2014 at 4:44 pm

    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

  37. Ankit
    August 22, 2014 at 6:10 am

    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.

    • Jimjiminy
      December 19, 2014 at 5:59 pm

      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).

  38. Greg Iles
    August 22, 2014 at 3:53 am

    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
      March 12, 2015 at 6:46 pm

      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.

    • Jay
      May 24, 2015 at 6:47 pm

      That is actually irrellevant as Verizon has had advanced calling. It's enables mobile data while on a call. They came up with that feature years ago when 3G was being being rolled out and AT&T turned up the heat as they were able to do that but Verizon wasn't.

  39. Dels
    August 22, 2014 at 3:10 am

    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

  40. elzafir
    August 22, 2014 at 1:48 am

    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).

  41. Tom W
    August 21, 2014 at 10:48 pm

    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
      August 22, 2014 at 4:32 pm

      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
      August 23, 2014 at 11:54 am

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

  42. Ant Man
    August 21, 2014 at 10:09 pm

    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
      August 22, 2014 at 6:42 pm

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