Is My Phone GSM or CDMA?

Follow these simple steps to figure out what kind of phone you have.

Easton Smith
Mobile, TV, & Moving Expert
February 28, 2022
4 min read

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You paid cold hard cash (or at least cold hard credit) for that new phone, which means you should be able to take it with you to a new carrier, right? Actually, it might depend on what kind of technology your phone uses: GSM or CDMA.

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.

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How to tell if your phone is GSM or CDMA

  • If you bought your phone from Verizon, then it is probably a CDMA phone.
  • If you bought it from AT&T or T-Mobile, it’s probably GSM.
  • Check your phone’s About settings.
  • Look up your phone’s model number online.
Two hands holding mobile phones

We’ll dive deeper into how to determine your phone’s technology in a moment. But first, what the heck is going on with all these capital letters?

What are GSM and CDMA phones?

You didn’t buy a cell phone so that you could worry about a bunch of technical gobbledygook. But knowing the difference between GSM and CDMA can help you avoid a big headache in the future.

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.


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Will GSM phones work on CDMA networks and vice versa?

The short answer is no.

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.

How to check what kind of phone you have

So, you’re asking yourself, “Is my phone GSM or CDMA?” Here are the easiest ways to find out.

Which carrier sold you the phone?

If you bought your phone from your carrier, then that can usually tell you what kind of technology it uses. Or, if you’re like me, and you inherited your stepdad’s old phone, then ask him where he originally got the device.

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.

Check your phone’s settings

It would be nice if your phone just said what kind of technology it used on the back, next to the model number. Unfortunately, it’s not quite that easy. But you can use your phone’s settings to figure out whether it’s GSM or CDMA.

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!).

Look up the model number

You can use those same About settings to find your model number on both iPhone and Android devices. Model numbers are also often printed on the back of your phone.

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.

Check for SIM card slot

There used to be a really easy way to determine what kind phone you had: just see if it has a SIM card slot. GSM phones did have SIM card slots, while CDMA phones didn’t.

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.

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The future of GSM vs. CDMA

As 5G networks are rolling out, carriers are beginning to shutter their old 2G and 3G networks. That means that GSM and CDMA technologies will become even less relevant.

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. 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.


GSM stands for Global System for Mobile communication. These phones typically require a SIM card to stay connected to that network.

CDMA stands for Code Division Multiple Access. Phones using this technology usually don’t use a SIM card since it is built in.

Verizon wireless typically uses CDMA phones, but sells phones that can use both GSM and CDMA.

T-mobile uses the GSM network.

AT&T uses GSM technology.


Now that you know, here are your next steps.

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Easton Smith
Written by
Easton Smith
Easton has worked as a freelance writer and researcher for several years, reviewing health, lifestyle, and technology products. He has probably read more Terms of Use contracts than any human alive. When he’s not sitting in front of a computer, Easton spends his time camping, climbing, and volunteering with humanitarian aid organizations.

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