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Large mobile companies use different wireless technologies which vary by carrier and region. The two main technologies currently in use are Code Division Multiple Access (CDMA), which is owned by Qualcomm, and Global System for Mobile (GSM) communications.
CDMA phones won’t work on GSM networks and vice versa. GSM offers the greatest speed and network capacity and is the most widely-used mobile network, including AT&T, T-Mobile and most other providers around the world. CDMA and GSM are similar in quality, but GSM (more so than CDMA) gives consumers more choices in equipment.
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GSM vs. CDMA mobile networks
Speed, quality and reception depend on equipment, location and service provider. Compared to CDMA, GSM is a more popular technology with availability in more than 200 countries worldwide. Both networks have their pros and cons.
Consumers, in general, seem to feel GSM is more convenient because it carries all of their data on a SIM card, so to change phones, you simply swap the SIM card into your new GSM phone.
With CDMA, on the other hand, it is not as easy to transfer phones because consumers are identified based on whitlelists (basically, a list of devices that are specifically authorized to access the network), not SIM cards. Some CDMA phones do use SIM cards, but they are more for the convenience of use outside the US. Besides, CDMA only allows approved phones on its networks.
What’s more, back in the 1990s, the FCC decided to make use of both CDMA and GSM technologies, while Europeeans and most of the rest of the world agreed on GSM.
GSM is working to overcome the perception that its networks do not offer the same high levels of security compared to CDMA, which experts say is difficult to detect even with targeted attacks.
CDMA devices emit much less radiation than GSM phones. In fact, GSM phones are said to expose users to 28 times the radiation levels compared to CDMA phones. This may be because GSM emits wave pulses continuously and CDMA phones do not.
CDMA is in use mostly in the U.S., Asia and Russia, whereas the GSM network is in virtually every country. CDMA phones also often have issues with roaming in some locations, but GSM phones rarely have that problem.
A full list of GSM carriers in the U.S. includes (in alphabetical order):
- Airfire Mobile
- Asset/Vada Wireless (uses AT&T/ TMobile)
- AT&T (Includes GoPhone Prepaid, Dobson Cellular, Edge Wireless and Centennial Wireless)
- Calhan Wireless
- Cellular One of East Central Illinois
- Cellular One of East Arizona
- Cellular One Nation
- Cellular One TXOK
- Chariton Valley Wireless
- Cincinnati Bell Wireless
- Commnet Wireless (also uses CDMA)
- Consumer Cellular (uses AT&T towers)
- Cordova Wireless
- Corr Wireless
- Cross Communications
- DTC Wireless
- Epic PCS
- Fuzion Mobile
- GCI Wireless (also uses CDMA)
- GTC Wireless (uses AT&T towers)
- i wireless
- Indigo Wireless
- Jolt Wireless (uses AT&T towers)
- KTC PACE
- Locus Mobile (uses CDMA, Verizon & AT&T towers)
- Long Lines Wireless
- Mobal Freedom (uses AT&T towers)
- NEP Wireless
- Pine Cellular
- Plateau Wireless
- Pure Prepaid (uses AT&T towers)
- Pure Talk USA (uses AT&T towers)
- Simple Mobile (uses T-Mobile towers)
- Shaka Mobile (also uses CDMA, Verizon and Sprint towers)
- Telecom North America Mobile Inc.
- T-Mobile USA
- TracFone Wireless (also uses CDMA, AT&T, Verizon, Sprint, US Cellular and T-Mobile towers)
- Tru (uses T-Mobile towers)
- Union Wireless
- Viaero Wireless
- Wal-Mart Family Mobile (uses T-Mobile towers)
- West Central Wireless
- XIT Communications
CDMA phones won’t work on the GSM network, and vice versa. In the U.S., Verizon and Sprint and their partners use CDMA. But, CDMA isn’t used as much overseas. So, if you’re on one of these networks and travelling overseas, your phone may not work. That said, many of the newer CDMA phones from Sprint and Verizon now have GSM compatibility and a SIM card, so if you’re planning a trip, it may be worth checking out if your phone will work.
GSM phones work on AT&T and T-Mobile networks as well as all their partner carriers that operate on the GSM network. GSM is overall a better bet when travelling internationally. You may have to contact your carrier, however, and get your phone unlocked so it will work on other mobile carriers around the world.
Is GSM better than CDMA?
People seem to prefer one mobile provider over another. Some like Sprint, while a next door neighbor prefers AT&T. Likewise, some people prefer Android over iPhone. There are also advantages and disadvantages with both CDMA and GSM.
Advantages of GSM
- Typically, equipment costs less
- Better reception and overall performance when travelling internationally
- Voice calls are of higher quality
- Compatibility with Integrated Services Digital Network (ISDN) — the integration of speech and data on the same lines
Advantages of CDMA
- Unlimited number of users
- Better overall security
- Signal is not affected by changing cells
- The fixed frequency spectrum is fully utilized
Disadvantages of GSM
- Questionable security
- Slower data transfers
- Limited number of users per each cell tower
Disadvantages of CDMA
- Decrease in quality as users increase
- Lack of international roaming
- Limited upgrade options
Keep in mind that although both CDMA and GSM have provided connectivity to millions of people for many years, as carriers roll out 5G, many will begin to phase out both networks. Verizon is already taking steps to begin transitioning CDMA devices off its network with the intent to eventually move all devices to the HD Voice LTE network.
For more insights into wireless matters and all things connected, be sure to bookmark our Resource Center.
By Kathryn Pomroy
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