Is GSM better than CDMA? These are the two most common mobile phone technologies. It offers an insurmountable barrier. They’re the reason that old AT&T phones won’t work on Verizon’s network and vice versa. 

What does GSM vs. CDMA imply for You?

GSM means “Global System for Mobiles” while CDMA means “Code Division Multiple Access”. These are abbreviations for two older radio technologies used in cell phones (also known as 2G and 3G). 

This article was first published in 2012, and it was updated during the 2010s. Then, it was critical to understand the differences between these two technologies. 

However, by 2021, it will be imperative to abandon CDMA and GSM. Those networks are being phased out! If your phone only supports 2G or 3G, you should upgrade to a 4G or 5G phone as soon as possible.

• AT&T has already decommissioned its 2G GSM network, and has just announced that it will decommission its 3G GSM/UMTS network in February 2022.
• T-Mobile will discontinue 3G GSM/UMTS service in April 2022 and 2G GSM service in December 2022.
• On January 1, 2022, T-Mobile will shut down the 3G CDMA network that certain Sprint and Boost customers utilize.
• Verizon’s 3G CDMA network will be decommissioned on December 31, 2022.

These networks are being turned down to levels primarily meant to support devices like electric meters and vending machines in their final years. 

Even before the formal shutdowns, 2G and 3G reception and call quality will most certainly be poor. It’s now a 4G LTE world, with 5G on the horizon. It’s time to upgrade, no matter how much you love your old phone.

Yes, there are still some 2G and 2G/3G phones for sale. Particularly  unlocked GSM phones. Do not purchase them. They’ll work inefficiently, and soon they won’t be able to work at all.

Weep not for CDMA and GSM. They’ve lived a long time. Sprint has a 25-year-old CDMA network.  In 1995, the first GSM network was launched in the United States. 

Generation (G) of Wireless Technology

There are now more effective ways to utilize our limited airwaves. 1G, 2G, 3G, 4G, 5G. When cell phone companies refer to a “G,” they’re referring to a wireless technology generation. Presently, we have 1 to 5th Generation.

Each generation is capable of supporting more users and transferring more data. Analog cellular phones were the first generation. Carriers had various competing alternatives when switching to 2G digital networks in the 1990s; some of them went out, but CDMA and GSM are the two 2G camps that have lasted. 

During the 2000s, they remained divided until the third generation. In principle, the CDMA/GSM separation ended in 2010. This is when all operators migrated to LTE, a single global 4G technology. 

However, the distinction remained because phones still required access to older 2G and 3G networks. they were mostly used for voice conversations. 

Voice calling over 4G was first introduced by AT&T, T-Mobile, and Verizon in 2014. However, it took some time. Voice over 4G is currently supported by all four carriers.

Carriers are now deploying 5G, which will be a single worldwide  standard termed 5G-NR after a few false starts. 5G is still in its infancy. Indeed, we’ve recently seen carriers instructing their own subscribers to turn it off if they don’t like it. 

However, 4G LTE is now fairly mature. If you’re still on 2G or 3G, upgrading to a 4G-compatible phone should be painless.

Compatibility Does not Imply Conformity to a Single Standard

LTE, or Long Term Evolution, is a 4G wireless protocol that is widely used around the world. It is used by all US carriers. 

Check out Mobile technology for Telephony devices.

Furthermore, all of the carriers adhere to the same 5G standard. So,  you’d think that’d make everyone compatible, right? Wrong.

Three Things are Required to be Compatible

• To support the same frequency bands-being able to listen to the proper channel to be using the same technology, similar to speaking the same language
• To gain access to the network. Everyone will utilize the same radio technology in the 4G and 5G worlds. But they may not have the same channels, and carriers may not allow other carriers’ equipment to be used on their networks.

The most significant issue is frequency band compatibility. Different radio channels are utilized by different carriers, therefore one carrier’s phone model may not contain channels used by other carriers. 

This is a common issue when traveling across foreign boundaries, as evidenced by the Samsung Galaxy S20’s six different international models. 4G devices that have not been certified by Verizon or AT&T have problems making calls or sending text messages over those networks. 

They’ll connect and get data, but they won’t be able to make phone calls. Many popular phones now support all three main carriers’ LTE networks, but not all.  Check out can 5G phone use 4G LTE.

All carriers support the Motorola Moto G4, E4, and later; Samsung Galaxy S7 and later; OnePlus 8 and later; and Google Pixel phones. 

All iPhone 6 and subsequent models are compatible with all LTE networks. Also, check out iPhone 5G and LTE Networks.

Yes, things are more complicated now than they were in the 2G era. GSM had the advantage of requiring the network to accept a phone if both the phone and the carrier followed the standard and the phone supported the appropriate channels. That is no longer the case.

Is GSM better than CDMA? Which Carriers are There?

Verizon, US Cellular, and the old Sprint network (now owned by T-Mobile) all employ CDMA in the United States. 

GSM is used by AT&T and T-Mobile. GSM is used by the majority of the remainder of the world. GSM’s global adoption was aided by the fact that the technology was mandated by legislation in Europe in 1987, and GSM was developed by an industry consortium. 

Qualcomm owns the majority of what we refer to as CDMA. Third parties were able to produce GSM equipment at a lower cost as a result of this.

So, why did so many carriers in the United States choose CDMA? Timing. CDMA was the newest, hottest, and quickest technology when Verizon’s predecessors and Sprint moved from analog to digital in 1995 and 1996. 

It had more capacity, better call quality, more promise than the GSM network of the time. GSM caught up, but those carriers’ courses had already been established. Switching from CDMA to GSM is possible. 

In Canada, Bell and Telus did it to have access to a wider range of off-the-shelf GSM phones. However, Verizon and T-Mobile are concentrating on 4G and 5G rather than 3G. Instead of switching, they’ll retire the older networks.

GSM and CDMA are Based on the Same Technology

Multiple-access technologies, such as CDMA and GSM, are both used. They’re devices that allow users to jam several phone calls or internet connections into a single radio station.

GSM was the first to arrive. It’s a system of “time division.” The calls are rotated. Your voice is converted to digital data, which is assigned a channel and a time slot. For example, three calls on one channel would look like this: 123123123123. 

On the other end, the receiver merely listens to the given time slot and reconstructs the call. When you put a GSM phone near a speaker, the pulsing of the time division signal produces the infamous “GSM buzz,” a buzzing sound. 

That’s essentially gone anymore, because 3G GSM isn’t a time division technology (as I’ll explain). CDMA, on the other hand, demands a little more processing power. 

It’s a system of “code division.” Every call’s data is encoded with a  unique key, and then the calls are all transmitted at the same time; for example, if a channel contains calls 1, 2, and 3, the channel will simply state 66666666. 

Each receiver has a unique key that allows it to “split” the combined signal into individual calls. Because code division proved to be a more powerful and adaptable technology, “3G GSM” is actually a CDMA technology known as WCDMA (wideband CDMA) or UMTS (Universal Mobile Telecommunications System) (Universal Mobile Telephone System). 

WCDMA, as the name implies, requires wider channels than prior CDMA systems, but it also provides more data capacity. (GSM is merely the official term for the 2G technology.) 

However, the term “WCDMA” is also commonly used to describe to any technology that follows the “GSM path” and has been certified by the same industry authority. Therefore, I’ll use it to refer to WCDMA.

GSM has progressed quicker than CDMA since its introduction. WCDMA is the third generation of GSM technology. The 3GPP (the  GSM regulatory body) has released HSPA extensions. It has theoretically increased the speed of GSM networks to 42Mbps.

Meanwhile, our CDMA networks were locked at 3.6Mbps. Faster CDMA technologies exist, but US operators choose to forego them in favor of 4G LTE, which is more compatible with international standards.

GSM vs. CDMA: What Does It Mean to You?

Now is the time to invest in a 4G LTE or 5G NR Phone. In the year 2021, GSM and CDMA should be irrelevant in purchase decisions. There have always been some significant disparities between the technologies. 

On GSM networks, swapping phones was significantly easier because customer information was stored on a removable SIM card. Remove the card and insert it into a new phone; the new phone now has your number. 

Furthermore, a carrier has to accept any GSM compliant phone to be considered GSM. So, the GSM providers didn’t have complete control over your phone.

With CDMA, however, this was not the case. CDMA operators in the United States utilize network-based white lists to authenticate their customers. That means you may only change phones with your carrier’s approval, and a carrier is not obligated to accept any phone onto its network. It’s possible, but most US carriers choose not to.

SIM cards are now standard on all US phones. However, this isn’t due to CDMA. Because the LTE standard also employs SIM cards. 4G LTE networks uses Sim card. Your phone or device almost probably has an eSIM if it doesn’t have a real SIM.

Verizon has made it more difficult to migrate a Verizon SIM from one device to another without first contacting Verizon. However, this has nothing to do with CDMA. Flags in Verizon’s 4G LTE provisioning systems are involved.

In general, 3G CDMA networks can be called EV-DO or Evolution Data Optimized. It could not perform phone calls and send data at the same time. Again, that’s an option (known as SV-DO for Simultaneous Voice and Data Optimization). But it’s not one that US carriers have accepted for their networks and phones. 

On the other hand, because it’s a requirement of the spec, all 3G GSM networks have simultaneous speech and data. Because Verizon 4G phones use LTE instead of CDMA, they can conduct both voice and data at the same time. Voice and data can be carried on all 4G and 5G networks at the same time.

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