In order to use REALLY's service, your device must be compatible, it can't be carrier locked and it needs to be eSIM compatible.
Check your device compatibility using our helpful link here!
Then you'll want to confirm your device is carrier unlocked.
How to check if your phone is carrier locked:
iPhone:
Open the Settings app
Tap the General section
Select About
Scroll down until you see Carrier lock
If you see "No SIM restrictions," your phone is unlocked. If you see something else in that section, your phone is carrier locked
Android:
Open the Settings app
Go to the Network & Internet, Connections, or a similarly labeled section
Select the Mobile network, Cellular network, or a similarly labeled section
Tap Advanced, Network operators, or a similarly labeled section
Toggle off the Select automatically, Choose network, or a similarly labeled section
If you see a list of carriers pop up when your phone searches for networks, your phone is unlocked. If you only see the name of your current carrier, your phone is carrier locked
And lastly, you'll want to be sure your device is eSIM compatible.
How to check if your device is eSIM compatible:
Most modern smartphones, especially flagship models from major brands like Apple, Samsung, and Google, typically support at least one eSIM.
Check our article Do you support eSIMs? for a list of the most common eSIM compatible devices.
If you're interested in a pSIM (physical SIM) check our Do you support physical SIMs (pSIM)? article.