Remove the right obstacle
Unlocking removes a provider restriction on using another eligible service. It does not add missing frequency support, repair radio hardware or override a device that a provider cannot support. Nor does it settle a finance agreement automatically.
Check the original provider's current unlocking policy and then the receiving provider's compatibility tool. Those checks answer different questions. Avoid a plan purchase based only on a seller's “unlocked” description.
Model details matter
A retail phone name can cover several regional variants. Voice features, eSIM support and Wi-Fi calling can also depend on software and provider configuration. Use the exact model or trusted IMEI checker rather than a photograph of the box.
For a second-hand handset, retain proof of purchase and a meaningful return route. A device can look clean and still have account or ownership restrictions. Do not ask an independent adviser to bypass those restrictions.
Test the features you will keep
After activation, test ordinary calls and SMS as well as mobile data. Check voicemail and any connected watch. If only one feature fails, describe that precisely to the provider; “the phone does not work” conceals useful diagnostic information.