The short answer
Verify unlock status with the device and carrier before relying on an online listing or moving to another network.
Step by step
Get the exact model, IMEI, original carrier, payoff status, and proof of purchase from the seller or account owner.
Check the phone's carrier-lock setting when the operating system provides one.
Ask the original carrier to confirm eligibility and unlock status using its official process.
Test another carrier's SIM or eSIM and complete its IMEI compatibility check.
Confirm calls, texts, and cellular data before the return window closes.
Before you finish
Keep screenshots, receipts, chat transcripts, confirmation numbers, and the first bill after a change. Carrier terms and account eligibility can change, so verify the final price and conditions directly before submitting an order.