Very few countries use CDMI, which was previously used by Verizon and Sprint. AT&T and T-Mobile have always used GSM, which is also the main standard used by most countries outside of the United States.

US carriers have historically used two wireless frequency standards, GSM and CDMI. To explain why we need to lightly delve into some cellular tech history. CDMAĪ phone may be unlocked and still not work with your carrier. Once you have your IMEI number, you can go to an IMEI checker site where you input your IMEI number and see if your phone is unlocked or not. Settings > General > About > IMEI (scroll down)Īlternatively, whether you're using an iPhone or Android, you can dial #06# then press call, and your IMEI number should appear. To find your IMEI number, you can do the following: If the search displays multiple networks, then your phone is most likely unlocked. Go to Settings > Connections > Mobile networks > Mobile operators > Search Now. Please note that this option isn't 100% foolproof - you may have an unlocked device but still not see 'Cellular Data Network.' Some phones will display Cellular Data Network once you click on 'Cellular.' If you don't see Cellular Data Network, your phone is probably locked. Go to Settings > Cellular > Cellular Data Options > Cellular Data Network.

If you see a message on the screen asking you for a SIM unlock code, then the phone is locked. There are several ways to check if your phone is really locked:Ī common solution is to turn off your phone, replace the current SIM card on your phone with another carrier's SIM card, and turn your phone back on. If you go to your carrier, and they tell you that your refurbished device is locked or even blacklisted, you can always double-check to make sure.

Verizon network locked sim card