Global System for Mobile Communications (GSM) was first deployed in Finland in 1991 and is commonly used around the globe with availability in more than 200 countries. 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's market share around the world is estimated to be less than 20%.
Between GSM and CDMA, one isn't particularly better than the other, and both ultimately provide the same services — the quality of service depends entirely on the carrier and not on whether GSM or CDMA was used.
A noticeable difference is that with a GSM phone, it can be unlocked so users can switch between carriers easily. With a CDMA phone, it'll be locked to a carrier and won't use a SIM card. Instead of an actual SIM card a CDMA phone will be linked to the network via a phone number.
Another difference is that on 2G and 3G networks, the GSM network allows you to make voice calls and transmit data at the same time, while CDMA does not. All carriers switched to LTE (long-term evolution) for 4G in 2010, which supports simultaneous voice and data use, regardless of whether their 2G and 3G connectivity was supported by GSM or CDMA networks.
And as major carriers continue to develop their 5G technology, the difference between GSM and CDMA won't matter. Fortunately, CDMA phones work on GSM networks, and that is why you’re able to use your Verizon phone when traveling to places where GSM is the standard, such as Europe, Asia, and South America.
Keep in mind that 3G networks for both GSM and CDMA will be totally defunct by 2022. AT&T's 3G network ended in February 2022. T-Mobile's 3G CDMA network (Sprint) ended in March 2022, and its entire 3G network by July 2022. And Verizon's 3G CDMA network will end by December 2022.
What does this mean for you?
Not much these days. As 5G (and then 6G) continues to develop around the world, the differences between GSM and CDMA won't matter.
GSM phone |
CDMA phone |
|
SIM |
A GSM phone can be unlocked so users can easily switch between carriers via SIM cards. |
A CDMA phone will be locked to a carrier, doesn't use a SIM card, and connects via a phone number. |
Coverage |
USA, International |
USA, International |
International Roaming |
GSM is commonly used around the world, and SIM cards can be easily switched when traveling. |
If traveling abroad, you can't switch SIM cards and will need to use your carrier's international roaming service, which can be costly. |
Since 4G and 4G LTE, and now the widespread deployment of 5G, the differences between GSM and CDMA (also known as 2G and 3G) matter less and less.
For example, because LTE (long-term evolution) requires a SIM card, even CDMA phones now have SIM card trays (or at the very least an eSIM). If in doubt about which phone is right for you, get in touch with us here or contact your carrier.