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GSM vs. CDMA: What You Need To Know About Phone Bands 

A detailed comparison between GSM vs CDMA technologies, highlighting their key differences, why phone bands are important, the pros and cons, and more. 
A city with lines showing the different network connections

Ever wondered why that old flip phone from 2005 won’t work on your current network? The answer lies in your phone’s technology. Older phones built for older 2G and 3G networks usually rely on either GSM or CDMA technology. And while some networks support CDMA, others only support GSM. Soon, both technologies will likely be obsolete.  

Confused? Don’t be! Read on to learn the difference between CDMA and GSM, what they are exactly, as well as the future of their network compatibility.  

CDMA vs. GSM  

CDMA stands for “Code Division Multiple Access.” GSM stands for “Global System for Mobiles.” They are two cellular network technologies used to transmit voice and data between mobile devices and cell towers.  

In the 1980s and 90s, as mobile technology became more advanced, there were two main radio systems adopted by carriers: CDMA (Code Division Multiple Access) and GSM (Global System for Mobile Communications). While CDMA offered advantages like better call reliability, GSM, which was first introduced in Europe, became more widely accepted around the world.  

In the U.S., carriers were split between adopting CDMA technology and the GSM network, which is why many devices could not be used across multiple carriers. CDMA technology relies on a unique identifier assigned to the phone itself to connect to a network. GSM uses a SIM card to identify the subscriber and maintain a connection to the network. These technologies operate on 2G and 3G networks. And while it’s possible to unlock some older GSM devices that operate only on 2G and 3G networks or purchase hybrids, those older phones likely will not work much longer in an increasingly 5G world.  

When we talk about 2G, 3G, 4G, and 5G networks, the “G” refers to “generation.” Older generations enabled voice calls and introduced text messaging, but the rise of 4G networks made possible the mobile capabilities we currently enjoy, such as high-speed internet, video, and messaging—all from the same handheld device. And as more and more devices become connected, 5G made its entrance—offering higher speeds and lower latency than ever before.  

So, what does this all mean for CDMA and GSM? Before we answer that, let’s take a closer look at both technologies. 

What’s the difference between CDMA and GSM?  

Here is the key difference between CDMA and GSM: CDMA networks use unique identifiers programmed into each device while GSM networks use SIM cards to authenticate devices and enable roaming, allowing users to use their devices in different countries without changing their phone number. 

To explain further, CDMA is one of the oldest technologies for cellular networks. In a CDMA network, each phone uses a unique code to transmit and receive data over the airwaves. The unique codes designated to each phone allow multiple users to share the same frequency band without interfering with each other, since the network can distinguish between users. CDMA is known for its high call quality and reliability, as well as its ability to support high-speed data services.  

However, throughout the 80s and 90s, GSM began to become the more popular choice for mobile networks, since it allowed even more users to share the same frequency bands. GSM introduced the use of the SIM (Subscriber Identity Module) card to identify the subscriber and maintain a connection to the network. SIM technology allows users to easily transfer information into a new device by moving the SIM card and roaming between different GSM networks across the globe.  

CDMA or GSM: Which is Better?  

For the average person, the question isn’t necessarily, “which technology is better?” It’s really, “which type of device does your network support?” If you have an older device, it’s possible that the device is only supported by one type of network. For example, when cellular technology was first going mainstream, US Cellular and the Sprint network (now owned by T-Mobile) used CDMA, while AT&T and T-Mobile used GSM. As devices evolved, dual-band phones (which can operate on both CDMA and GSM networks) emerged. However, some key differences exist between the two.  

For example, CDMA networks tend to have better coverage and capacity, but GSM networks are more widely used around the world, making it easier to stay connected while traveling, especially to different countries. Outside the U.S., CDMA phones are more difficult to find, since the European Union declared GSM as the standard in 1987.  

Though the split between CDMA technology and GSM kept devices siloed through much of the early 2000s, the introduction of LTE (long-term evolution) meant that most carriers prioritized a global 4G standard. These 4G networks made it easier to compress more information, which made it possible to browse the internet, talk, text, and send data from phones at faster speeds. But some carriers still rely on 2G and 3G networks (which support CDMA and GSM) in areas where 4G coverage is sparse. Now, as the industry begins to turn  to 5G—GSM and CDMA technology is becoming increasingly obsolete. 

The future of CDMA vs. GSM  

The successor to 4G networks is 5G, which network providers began rolling out worldwide in 2019. 5G networks offer faster speeds and lower latency, meaning that networks will be able to handle the much higher demands of an increasingly connected world. Though the 2G and 3G networks that support CDMA and GSM devices still exist, they are frequently being phased out.  

For example, some carriers have shut down their 2G and 3G networks entirely, and phones that ran on these networks no longer work. Other devices may need a replacement SIM to continue working properly. But, even if some carriers continue to support 2G and 3G networks, the level of support is usually lower than it has been in the past. This means older devices that aren’t designed for 4G or 5G will likely experience much worse reception than they have previously.  

The Solution  

As older phones that run on older networks become obsolete, it might be time to switch to a device that supports 5G, as it’s certainly your best bet for staying connected now and in the future. 

Not ready to trade in your old phone just yet? To stay connected as long as possible, make sure you know whether your phone is CDMA or GSM. A quick Google search of the model number will tell you what kind it is. Here’s another way to check: 

iPhone: Go to Settings, click on General and then About, and look for an MEID, ESN or IMEI number near the bottom of the menu. 

Android: Go to Settings, click on About phone, then scroll to Status and look for an MEID, ESN or IMEI number. 

  • MEID or ESN number = CDMA 
  • IMEI number = GSM 
  • If you see both, your device supports both CDMA and GSM

The next question is: how long will your phone continue to work with your current provider? You can check their website for a list of compatible devices, as well as their plans for the future of their networks. Many carriers also notify customers whose devices will no longer be supported well in advance. 

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