While most phones sold across the world are GSM phones, there are some notable exceptions. Here’s a peek at some of the easiest ways to tell what sort of technology your phone uses. GSM stands for Global System for Mobile communication. CDMA stands for Code Division Multiple Access. Those are just fancy ways of describing two forms of radio technology that phones and phone networks use to transmit voice and data. One of the biggest differences between these two systems is that GSM phones use SIM cards to link a particular phone with its network, while CDMA phones don’t require a SIM card because the phone itself is linked to the network. However, with the widespread adoption of 4G LTE networks, this has changed. The GSM vs. CDMA debate was really only about 2G and 3G technology. Now that 4G (and 5G) are the standards, phone manufacturers like Apple, Google, and Samsung are creating devices that are compatible with all phone technologies: CDMA, GSM, LTE. 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. A locked phone can be unlocked to work on other networks, but only networks that are compatible with the phone’s technology. However, as mentioned above, if you have a newer phone, like a Galaxy S20 (or even an iPhone 6s), it will often be compatible with all three technologies as long as it is unlocked. While AT&T and T-Mobile sell GSM phones. Verizon uses CDMA technology in its networks, but usually sells phones that are equipped with both technologies. If you bought your device “factory unlocked” or directly from the manufacturer, then it is likely equipped with both technologies. How to check whether your phone is GSM or CDMA using settings:
On an iPhone: Go to the Settings app, click on General and then About, and look for an MEID, ESN, or IMEI number near the bottom of the menu. On an Android device: Go to Settings, click on System and then About phone, then click on Status and look for an MEID, ESN, or IMEI number.
If your phone has an MEID or an ESN number, it’s CDMA. If you see an IMEI number then it’s GSM. If you see both, then your device supports both technologies (lucky you!). Once you’ve got your model number you can use a simple Google search to find out if it’s a GSM or CDMA phone. Here’s what it looked like when I looked up my iPhone 6 model. However, since the widespread adoption of 4G LTE technology, most phones use SIM cards, even CDMA devices. So, while this trick is less helpful now, it still applies that if your phone doesn’t have a SIM card slot (either in the side or in the back with the battery), then it’s almost certainly a CDMA device. In fact, most major US wireless carriers have been in the process of shutting down their 3G networks over the last couple of years. Verizon has stated that they will be officially shutting down their CDMA 3G network by December 31st, 2022. 1 This impacts 3G phones and possibly some 4G devices. If you have an older phone that is still on a 3G network, you should check with your carrier about their plans to shut down these networks and how it will impact you.
