Is My Phone Compatible With Verizon, T-Mobile or AT&T? BYOD Check Before You Switch

To find out whether your phone is compatible with Verizon, T-Mobile or AT&T, enter its IMEI (dial *#06#) into the carrier’s own bring-your-own-device checker. A phone passes when it is unlocked, not reported lost or stolen, supports the carrier’s 4G LTE and 5G bands, and supports VoLTE calling on that network. Most recent unlocked iPhones and US-model Samsung and Pixel phones pass on all three.

When the checker says “not compatible” or “not eligible”, the reason is almost always one of a short list — a carrier lock, a blacklist entry, an unpaid balance, missing bands or an uncertified import. This guide shows how to check each one before you port your number, so you don’t switch and end up with an unlocked phone with no service.

The official BYOD compatibility checkers

Each carrier runs its own IMEI check, and it’s the only answer that counts for activation. Have your IMEI ready (Settings › General › About on iPhone, Settings › About phone on Android, or dial *#06#). On dual-SIM phones, use the first IMEI unless the checker asks for both. See how to find your IMEI if you’re stuck.

Prepaid brands and MVNOs have their own checkers (for example T-Mobile Prepaid at prepaid.t-mobile.com). Use the checker of the exact brand you’re joining, because the list of approved devices can differ even on the same network.

Why does my IMEI say not eligible or not compatible?

Carriers rarely explain the result in detail. These are the usual causes, roughly in order of how often they show up.

1. The phone is still locked to another carrier

A locked phone only works on the carrier that sold it. On an iPhone, open Settings › General › About › Carrier Lock: you want No SIM restrictions. On Android, insert a SIM from another carrier and see if it’s rejected. A carrier and SIM-lock check confirms the lock status and the original carrier from the IMEI. Our carrier-locked vs unlocked guide explains the difference in detail.

2. The IMEI is blacklisted

If a phone was reported lost or stolen, carriers block it across the US — T-Mobile’s checker literally shows “Device Blocked”. Run a GSMA blacklist check if you bought the phone used. For Verizon phones, the Verizon clean/lost check shows Verizon’s own status, and the T-Mobile / generic check covers T-Mobile. Only the carrier that blocked it can remove the report, usually at the request of the original owner — see can a blacklisted phone be unblocked?

3. There’s an unpaid balance

Phones still on an installment plan stay locked, and a phone whose balance went unpaid when the owner left can be blacklisted for non-payment. This catches many used-phone buyers. Ask the seller for proof the phone is paid off, and check the blacklist before you buy.

4. The phone lacks the right bands

A phone built for another region may not support the frequencies a US carrier relies on. It may still connect in some places, but with weak indoor coverage or no 5G. More on bands below.

5. It isn’t certified for VoLTE on that network

All three carriers have shut down 3G, so voice calls now run over LTE (VoLTE) or 5G. A phone that can’t make VoLTE calls on a given network is effectively useless there, even if data works. Carriers maintain lists of devices they’ve tested; imported or niche Android models often aren’t on them.

6. It’s a very old or CDMA-only model

AT&T’s own guidance is that CDMA phones won’t work. Old Verizon-only devices without VoLTE fall into the same trap.

Will an unlocked phone work on any carrier?

Not automatically. “Unlocked” only removes the software restriction. The phone still has to speak the carrier’s radio frequencies and be recognised by its network for voice calls. In practice:

• Unlocked iPhones (iPhone 11 and newer) work on all three US carriers, because Apple builds US models with the bands for all of them and Apple devices are certified across the board.
• US-model Samsung Galaxy and Google Pixel phones sold unlocked by the manufacturer generally work on Verizon, T-Mobile and AT&T.
• Imported Android phones — Chinese, Indian, European or global variants of Xiaomi, OnePlus, Samsung and others — are the risky group. They may lack key US bands or VoLTE approval, and the checker may reject them even when they’re unlocked.

If you’re looking at an Android import, a carrier check plus the manufacturer’s spec sheet (look for the exact model number’s band list) tells you far more than the word “unlocked” in a listing.

Network bands that matter on Verizon, T-Mobile and AT&T

You don’t need to memorise frequencies, but a few bands decide whether a phone works well in the US. Compare them with your phone’s exact model number on the manufacturer’s spec page.

A phone missing band 13 will struggle on Verizon; one missing band 71 and n41 will feel slow and patchy on T-Mobile; one missing band 2, 4/66 and 12/17 will struggle on AT&T. Band lists vary between variants of the same phone, so always check the exact model number.

Switching carriers and keeping your phone: unlock rules in 2026

If your phone came from a carrier, unlock it before you switch. The rules differ, and they changed in 2026. According to Droid Life’s January 2026 comparison of the three policies:

Verizon’s change followed an FCC waiver in January 2026 that ended its old rule of unlocking phones automatically after 60 days. Details are in our Verizon unlock policy guide. After the old carrier confirms the unlock, Verizon notes it can take up to 24 hours before the device activates on its network — so don’t panic if the first attempt fails.

eSIM-only iPhones and eSIM transfer when switching

Every iPhone sold in the US since the iPhone 14 (2022) is eSIM-only — there’s no SIM tray. The iPhone 18 Pro and Pro Max, released 18 September 2026, are eSIM-only in the US, Canada, Mexico, Japan and several Gulf countries. That doesn’t change compatibility, but it changes how you switch:

• Activate online or in the carrier’s app. T-Mobile says eSIM-ready phones can activate instantly; the others are similar.
• Don’t delete your old eSIM until the new line works. If the port fails, your old eSIM is your fallback.
• Keep your old account number and transfer PIN ready. You need them to port your number, and the new carrier won’t proceed without them.
• Some international eSIM-only phones behave differently. An iPhone bought abroad works in the US on eSIM if it’s unlocked; a physical-SIM model from overseas also works with a US SIM card.

For step-by-step instructions, including Quick Transfer between iPhones and moving an eSIM to Android, see our eSIM setup and transfer guide. If your iPhone shows “SIM not supported”, read what SIM not supported means.

Phones bought abroad and MVNOs

Phones from abroad

An unlocked iPhone from Europe, Asia or Nigeria will generally work on US networks, because Apple’s international models share most bands. Android phones bought abroad are hit-and-miss: check the exact model’s band list and run the carrier’s IMEI checker before you rely on it. The same logic works in reverse — our guide to using a US iPhone abroad covers taking an American phone overseas.

MVNOs and prepaid brands

MVNOs rent capacity on the big three. Visible and Total Wireless run on Verizon, Mint Mobile runs on T-Mobile, Cricket runs on AT&T, and some, like US Mobile, offer more than one network. Your phone must be compatible with the underlying network and pass the MVNO’s own checker. MVNOs sometimes have stricter device lists — some don’t support every eSIM device or Wi-Fi Calling on imported phones.

Step-by-step BYOD compatibility check before you switch

1. Find your IMEI. Dial *#06# or look in Settings. Write down every IMEI listed.
2. Check the lock status. iPhone: Settings › General › About › Carrier Lock. Or run a carrier and SIM-lock check.
3. Check the blacklist. Especially for used phones: a GSMA blacklist check takes seconds.
4. Confirm the phone is paid off. Ask your current carrier for the payoff balance, or get proof from the seller.
5. Run the new carrier’s IMEI checker. Use the exact brand you’re joining (Verizon, Visible, T-Mobile, Mint, AT&T, Cricket…).
6. Check the bands for imports. Compare your exact model number against the table above.
7. Request the unlock if needed and wait for confirmation (up to 24 hours on Verizon’s side).
8. Get your account number and transfer PIN from your current carrier.
9. Back up the phone, then activate the new eSIM or SIM and port your number. Keep the old line until calls, texts and data all work.

Five minutes of checking before you switch saves you from the worst case: a ported number, a cancelled old plan, and a phone that won’t make calls. If you’re buying a used phone to bring to a new carrier, run these checks before you pay.