How do I unlock my iPhone to use with my carrier's SIM card?

To unlock your iPhone for use with another carrier, you must contact the original cellular provider the device was locked to and request an official unlock. Apple is unable to perform carrier unlocks directly. Once the carrier confirms the request has been processed, you may need to connect your iPhone to a Wi-Fi network or restore it using a computer to finalize the process. If you are unsure which carrier originally sold the phone, you can use an IMEI lookup service or contact Apple Support for assistance.