CDMA vs. GSM: What's the Difference? (2023)

Two basic technologies inmobile phones, CDMA and GSM, represent a gap you can't cross. They're the reason you can't use old AT&T phones on Verizon's network and vice versa. But what does CDMA vs. GSM really mean for you?

CDMA (Code Division Multiple Access) and GSM (Global System for Mobiles) are shorthand for two older radio systems (also known as 2G and 3G) used in cell phones. We first published this article in 2012 and kept it updated it throughout the 2010s, when it was important to know the differences between these two technologies. But in 2022, it's absolutely time to get off of CDMA andGSM. Those networks are going away! If you have a phone that only uses 2G or 3G, you need to get a 4G or 5G phone, pronto.

In the twilight years of these networks, they're being turned down to levels primarily designed to support devices like electric meters and vending machines. That means 2G and 3G reception and call quality will likely be poor, even before the formal shutdowns. It's a 4G LTE world now, with 5G coming up fast. No matter how much you love your old phone, it's time to switch over.

Yes, there are some 2G-only and 2G/3G-only phones still for sale, especially unlocked GSM phones. Don't buy them. They'll work poorly, and pretty soon they won't work at all.

Don't weep for CDMA and GSM. They've had long lives. Sprint's CDMA network is 25 years old(Opens in a new window). The first GSM network launched in the US in 1995(Opens in a new window). There are more efficient ways to use our limited airwaves now.

1G, 2G, 3G, 4G, 5G

When cell phone providers talk about a "G," they mean a generation of wireless technology. Each generation is able to support more users and has better data transfer capabilities.

The first generation was analog cellular phones. When carriers switched to 2G digital systems in the 1990s, they chose among several competing options; some of them died out, but CDMA and GSM are the two 2G camps that survived. They remained split during the '00s through the third generation of cellular, which added better data speeds but stayed incompatible.

The CDMA/GSM split ended, in theory, as carriers all switched to LTE, a single, global 4G standard, starting in 2010. But the difference remained because phones still needed to access the older 2G and 3G networks, primarily for voice calls. AT&T, T-Mobile, and Verizon all started to phase in voice calling over 4G in 2014, but it took a while. All four carriers now support voice over 4G.

Now carriers are installing5G, which (after a few false starts) will be a single global standard called 5G-NR. 5G is still in the early stages. You can't make voice calls over it quite yet, and it doesn't have true nationwide coverage. But 4G LTE is very mature now, and if you're still on 2G or 3G, you should have no concerns about upgrading to a 4G-compatible phone.

CDMA vs. GSM: What's the Difference? (1)

The Samsung Galaxy S20 and its siblings were the first all-carrier 5G phones for the US

One Standard Doesn't Mean Compatibility

LTE, or Long Term Evolution, is the globally accepted 4G wireless standard. All of the US carriers use it. For more, see3G vs. 4G: What's the Difference?

(Video) CDMA vs. GSM: What's the Difference?

And all of the carriers use the same 5G standard. (For more on that, see ourexplainer on 5G.) So you'd think, hey, that should make everyone compatible, right? Wrong.

To be compatible, you need three things:

In the 4G and 5G world, everyone will be using the same radio technology, but they may not have the same channels, and carriers may not permit other carriers' devices to be used on their networks.

The biggest problem is frequency band compatibility. Carriers operate on different radio channels, and one carrier's model of a phone may not include channels used by other carriers. This is frequently a problem across international borders, as with the six different international models of the Samsung Galaxy S20.

On Verizon and AT&T, 4G devices that haven't been certified by the carrier have trouble making voice calls or sending text messages over that network. They'll connect and get data, but they can't make calls.

AT&T has a list of which phones will work(Opens in a new window) when it turns off 3G.

Many, but not all, popular phones now support all three major carriers' LTE networks. TheMotorola Moto G4,E4, and later; theSamsung Galaxy S7and later; the OnePlus 8 and later; and Google Pixel phones all work across all carriers. For iPhones, all iPhone 6 and later phones work on all carriers' LTE systems.

Yes, this is more complicated than the old 2G world. One advantage of GSM was that if a phone and carrier both adhered to the standard, and the phone supported the right channels, the network had to accept the phone. That isn't the case any longer.

CDMA vs. GSM: What's the Difference? (2)

Verizon has replaced most of its 3G network with 4G, but some pockets still remain (see West Virginia here)

Which Carriers Are CDMA? Which Are GSM?

In the US, Verizon, US Cellular, and the old Sprint network (now owned by T-Mobile) used CDMA. AT&T and T-Mobile used GSM.

Most of the rest of the world used GSM. The global spread of GSM came about because in 1987, Europe mandated the technology by law, and because GSM comes from an industry consortium. What we call CDMA, by and large, is owned by chipmaker Qualcomm. This made it less expensive for third parties to build GSM equipment.

(Video) CDMA vs. GSM: What's the Difference?

So why did so many US carriers go with CDMA? Timing. When Verizon's predecessors and Sprint switched from analog to digital in 1995 and 1996, CDMA was the newest, hottest, fastest technology. It offered more capacity, better call quality, and more potential than the GSM of the day. GSM caught up, but by then those carriers' paths were set.

It's possible to switch from CDMA to GSM. Bell and Telus in Canada did it to get access to the wider variety of off-the-shelf GSM phones. But Verizon and T-Mobile are focused on 4G and 5G, not 3G. They are retiring the older networks rather than switching.

CDMA vs. GSM: What's the Difference? (3) What Is 5G?

The Technology Behind CDMA and GSM

CDMA and GSM are bothmultiple-accesstechnologies. They're ways for people to cram multiple phone calls or internet connections into one radio channel.

GSM came first. It's a "time division" system. Calls take turns. Your voice is transformed into digital data, which is given a channel and a time slot, so three calls on one channel look like this: 123123123123. On the other end, the receiver listens only to the assigned time slot and pieces the call back together.

The pulsing of the time division signal created the notorious "GSM buzz," a buzzing sound whenever you put a GSM phone near a speaker. That's mostly gone now, because 3G GSM (as I'll explain) isn't a time division technology.

CDMA requires a bit more processing power. It's a "code division" system. Every call's data is encoded with a unique key, then the calls are all transmitted at once; if you have calls 1, 2, and 3 in a channel, the channel would just say 66666666. The receivers each have the unique key to "divide" the combined signal into its individual calls.

Code division turned out to be a more powerful and flexible technology, so "3G GSM" is actually a CDMA technology, called WCDMA (wideband CDMA) or UMTS (Universal Mobile Telephone System). WCDMA requires wider channels than older CDMA systems, as the name implies, but it has more data capacity.

(GSM is actually only the formal name for the 2G system. But the name is also widely used to refer to any technology on the "GSM path" and approved by the same industry body, so I'm referring to WCDMA as 3G GSM so people don't confuse it with the separate 2G CDMA.)

Since its inception, GSM evolved faster than CDMA. WCDMA is considered the 3G version of GSM technology. The 3GPP (the GSM governing body) released extensions called HSPA, which sped GSM networks up to as fast as 42Mbps, at least in theory.

Our CDMA networks, meanwhile, got stuck at 3.6Mbps. Faster CDMA technologies exist, but US carriers chose not to install them and instead turned to 4G LTE to be more compatible with global standards.

CDMA vs. GSM: What's the Difference? (7)

The Alcatel Go Flip 3 makes calls over 4G LTE

Why Carriers Are Shutting Down 2G and 3G

Everyone's scrolling, Snapping, texting, FaceTiming, and more. Demands for mobile data use continue to rise. 2G and 3G, CDMA and GSM, are inefficient uses of the airwaves. 4G and 5G compress more information into each hertz of airwaves, and can combine channels much more flexibly for more efficient operation. So the carriers are retiring the older, less efficient technologies in exchange for newer networks which make better use of a scarce resource.

The carriers believe that most people have already switched to 4G through the natural process of upgrading phones. Phones making 4G voice calls have been in the market for years now. Apple's first iPhone with 4G voice was the iPhone 6, from 2014. While it's annoying to have to switch out an older phone because of this network transition, it's far from sudden.

(Video) Wireless Basics - GSM, CDMA, and LTE

There's no technological difference between "CDMA" and "GSM" carriers any more in the age of 4G LTE and 5G. Some cultural differences remain, though.

Specifically, Verizon makes it really hard to move your SIM card between devices without their permission, while it's easier to do so on AT&T and T-Mobile. That's an option in 4G. Verizon does it because historically, with CDMA, it could control which phones were on its network, and it wants to keep as much of that control as possible. AT&T and T-Mobile don't in part because in the GSM era, the GSM spec meant they had to accept anyone with a compatible phone.

Ready to Upgrade?

To find the right phone and carrier for you, ourReaders' ChoiceandFastest Mobile Networksawards are great places to start, along with our list of the best phones we've tested.

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FAQs

Which is better GSM or CDMA? ›

The data speed rate of GSM is 384 kbps using the EDGE data transmission technology. High-Speed Packet Access (HSPA) has a data transfer speed of up to 42 Mbps. CDMA on the other hand has a data speed rate of 2 Mbps employing EVDO technology. This means that the speed rate of CDMA is higher than GSM's.

Can I use a GSM SIM card in a CDMA phone? ›

The short answer is no. If you have an older device that is only equipped with GSM technology, it will never work well on CDMA networks like Verizon, even if it's an unlocked phone. If you have a phone that's CDMA only then it won't work well on GSM networks, like AT&T and T-Mobile.

Is 5G CDMA or GSM? ›

Comparison table
GenerationTechnologySignal quality/coverage area
3GW-CDMASmaller cells and lower indoors coverage on 2100 MHz; equivalent coverage indoors and superior range to GSM on 850/900 MHz.
4GOFDMASmaller cells and lower coverage on the S band.
5GOFDMADense cells on millimeter waves.
4 more rows

Which carriers use GSM vs CDMA? ›

Well GSM networks like US Mobile, T-Mobile, and AT&T use removable SIM cards. This means that unlocked phones from other American GSM carriers will work on US Mobile's network. On the other hand, Verizon and Sprint are CDMA carriers. CDMA carriers don't use SIM cards and most CDMA phones are locked into their network.

Why is CDMA not popular? ›

It's more of a network issue. Much lesser networks supporting CDMA, which in turn makes less market for CDMA phones. In India, CDMA networks are literally non existent.

Who uses CDMA network? ›

Which Carriers Are CDMA? Which Are GSM? In the US, Verizon, US Cellular, and the old Sprint network (now owned by T-Mobile) used CDMA. AT&T and T-Mobile used GSM.

What happens if you put CDMA SIM in GSM phone? ›

CDMA phones are compatible with 2G/3G CDMA networks, while GSM phones only work with 2G/3G GSM networks. So if you want to use your CDMA device on a GSM network, it won't work. As such, it's essential to know what kind of technology your phone uses.

Can a phone be both GSM and CDMA? ›

Most newer phones work with both GSM and CDMA technologies, so you don't have to worry about what kind of phone to get or which carrier to switch to.

Does 4G use CDMA or GSM? ›

4G LTE is neither CDMA nor GSM but a separate cellular technology that provides the 4G migration path to 3G networks on CDMA and GSM tracks. CDMA2000 is the 3G technology on the CDMA track, and UMTS is the 3G technology on the GSM track. Both UMTS and CDMA2000 use the LTE technology for 4G services.

Which carriers use GSM phones? ›

Both T-Mobile and AT&T use the GSM network, and therefore sell GSM-compatible phones. However, if you have a phone made in the last couple of years, you probably don't need to worry about which carriers use GSM or CDMA networks since most newer phones work on both networks.

Why is CDMA preferred over GSM? ›

The signal cannot be traced easily in CDMA as compared to the signals of GSM, which are concentrated in the narrow bandwidth. Therefore, CDMA phone calls are more secure than GSM calls. In terms of encryption, GSM technology has to be upgraded so as to make it operate more securely.

Does Verizon still use CDMA? ›

3G CDMA Network Retirement

As previously communicated, Verizon is actively decommissioning our 3G CDMA network. We expect this to be completed by no later than December 31, 2022. This decommissioning effort affects 3G (CDMA) devices, 4G Non-VoLTE devices, and network extenders.

Does anyone still use CDMA? ›

CDMA is one of two cellular technologies that help bridge the gap when there's no 4G signal. Verizon (and previously Sprint) currently use the CDMA network. MVNOs are growing in popularity because they operate on the main US networks to give you the same nationwide coverage but low monthly costs.

What is the disadvantage of CDMA? ›

In CDMA, time synchronization is required. It can't offer worldwide meandering, a huge GSM advantage. The CDMA framework execution debases with an expansion in the quantity of clients.

Are CDMA phones going away? ›

T-Mobile announced that it finished shutting down Sprint's 3G CDMA network as of March 31, 2022 and Sprint's 4G LTE network as of June 30, 2022. It also announced it shut down T-Mobile's 3G UMTS network as of July 1, 2022, but has not yet announced a shutdown date for its 2G network.

Does 4G uses CDMA? ›

CDMA is a set of protocols used in 2G and 3G mobile communication networks. LTE is a protocol used in 4G broadband technology; it provides high-speed data access. CDMA is a set of protocols for 2G/3G wireless communication. LTE is nowadays the de-facto standard for 4G high-speed wireless communication.

Does Verizon use GSM now? ›

AT&T and T-Mobile are GSM wireless networks. Code-division multiple access (CDMA) is used mainly in the US. Verizon uses CDMA technology and is the largest wireless carrier in the US, but CDMA market share around the world is estimated to be less than 20%.

Why do we use CDMA? ›

CDMA optimizes the use of available bandwidth as it transmits over the entire frequency range and does not limit the user's frequency range. It is used as the access method in many mobile phone standards.

Can GSM phones use LTE? ›

Long Term Evolution (LTE)- A cell phone standard used to define the fourth generation of mobile communication for GSM and CDMA networks. Time Division Multiple Access (TDMA)- A method used to manage the users accessing a frequency channel on TDMA-based networks.

Can CDMA phones be unlocked? ›

CDMA phones must be flashed in person using a cable in order to get it to use a different CDMA network. The unlocking codes can be received from the manufacturer of the phone, or through a keygen program. This means the phone can be unlocked remotely with such a code.

Are unlocked phones GSM or CDMA? ›

All unlocked phones work on carriers that use GSM networks. Popular U.S. carriers that use GSM networks include AT&T, T-Mobile, Cricket, MetroPCS, Simple Mobile and Tracfone. Most foreign carriers also use GSM networks.

How do I know if my SIM card is GSM or CDMA? ›

Method 2 – Go to the Settings App

You're looking for anything regarding a MEID, ESN, or IMEI number. MEID and ESN numbers are associated with CDMA networks. Finding an IMEI number means the phone is configured for GSM networks.

Is Verizon GSM or CDMA 2022? ›

While CDMA is used widely in the U.S., it is less common elsewhere — most estimates pin the portion of global wireless networks using CDMA at less than 20 percent. The Verizon network is a CDMA wireless network.

Is GSM same as LTE? ›

GSM is the classic radio communication system in mobiles, whereas LTE is primarily the next generation of wireless technology for the system of cellular mobile communication. LTE and high-speed data transmission go hand in hand. LTE supports only data transmission, whereas GSM supports both data and voice.

Why is CDMA preferred over GSM? ›

The signal cannot be traced easily in CDMA as compared to the signals of GSM, which are concentrated in the narrow bandwidth. Therefore, CDMA phone calls are more secure than GSM calls. In terms of encryption, GSM technology has to be upgraded so as to make it operate more securely.

Why is GSM used over CDMA? ›

It uses the Code division multiple access (CDMA). GSM supports the transmission of both voice and data at once. The CDMA technology does not support any such feature. It cannot transmit voice and data simultaneously.

Is CDMA safer than GSM? ›

Exposure to Radiation

GSM based phones emit 28 times more radiation as compared to CDMA phones. Continuous exposure to radiation can affect your health. So, CDMA phones are considered safer than GSM.

What network mode should I use? ›

Tap the appropriate setting:
  1. Global. : This is the preferred setting for most locations.
  2. LTE/CDMA. : This setting should only be selected if experiencing service issues in locations that offer multiple network types and only LTE/CDMA is needed.
  3. LTE/GSM/UMTS.

What is the disadvantage of CDMA? ›

In CDMA, time synchronization is required. It can't offer worldwide meandering, a huge GSM advantage. The CDMA framework execution debases with an expansion in the quantity of clients.

Is Verizon still using CDMA? ›

3G CDMA Network Retirement

As previously communicated, Verizon is actively decommissioning our 3G CDMA network. We expect this to be completed by no later than December 31, 2022. This decommissioning effort affects 3G (CDMA) devices, 4G Non-VoLTE devices, and network extenders.

Can a phone be both GSM and CDMA? ›

If your phone has a MEID or ESN number, it uses CDMA, and if it has IMEI, it uses GSM. If you see both, that means your phone supports both GSM and CDMA networks.

Does LTE use GSM or CDMA? ›

The LTE standard is a fourth-generation network technology that allows mobile networks on GSM and CDMA tracks to migrate to 4G. LTE is neither GSM nor CDMA but a separate technology that provides the 4G migration path to 3G UMTS and 3G CDMA2000 networks.

Does 4G use CDMA or GSM? ›

GSM/UMTS, CDMA/CDMA200, and LTE are mobile standards that were developed to work with different networks. GSM and CDMA were used to move into the 2G network, while UMTS and CDMA2000 were used to transition into the 3G network. LTE, on the other hand, migrates CDMA/CDMA2000 and GSM/UMTS into the 4G network.

Is Verizon GSM or CDMA 2022? ›

After years of delays, Verizon says it will finally shut down its 3G CDMA network at the end of 2022 — and the company means it this time. Verizon initially targeted 2021 for the shutdown and later revised with a more ambitious goal of 2019.

Does anyone still use CDMA? ›

CDMA is one of two cellular technologies that help bridge the gap when there's no 4G signal. Verizon (and previously Sprint) currently use the CDMA network. MVNOs are growing in popularity because they operate on the main US networks to give you the same nationwide coverage but low monthly costs.

Why does Verizon use CDMA? ›

Verizon Wireless Services

CDMA is a more reliable signal and the towers do not have to be as close to each other for hand off as they do for GSM.

Can a GSM phone be hacked? ›

Yes, your phone can be hacked — and it happens more often than you might think. But there are ways to tell if you've been the victim of a phone hack, and precautions to take to avoid being hacked in the first place. In this article, we'll show you how to protect yourself against phone hacking.

What network type should I use on my phone? ›

Although 4G is recommended, as stated above, it can use more of your data more quickly in a given time frame. Most apps and mobile services operate on both 4G and 3G without problems. You can also change the DNS settings on your Android.

Does Verizon Wireless use CDMA or GSM? ›

The Verizon network is a CDMA wireless network.

Is Verizon switching to GSM? ›

Your question: “When will Verizon Wireless switch to GSM in the US?” They have NO reason to do so - ever. The “CDMA Carriers” Verizon, Sprint, etc., are migrating from their current CDMA protocol technologies of 2G 1xRTT and 3G EV-DO to 4G LTE without doing any 2G GSM or 3G UMTS deployments.

Videos

1. CDMA vs GSM in US (short version)
(RandoTechInfo)
2. What GSM and CDMA Mean for You and Your Cell Phone
(Clark Howard: Save More, Spend Less)
3. What are the differences between CDMA vs. GSM smartphones?
(Dr.E (Max Lee))
4. CDMA vs GSM What's the Difference
(Whatsapp FAQ)
5. Mobile Network Types as Fast As Possible
(Techquickie)
6. GSM VS CDMA: Important Difference in GSM & CDMA Technology
(Computer Science Academy By Dinesh Sir)
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