How can I unlock my SIM carrier locked iPhone SE (2nd generation)?

In a case like this the history of the device is the most important. If you purchased this device used, then your best option is to return it if you can. You are unlikely to get any information from the carrier that locked it. You don't know the details of the contract that locked the device to the carrier and whether that customer had met the obligations to have the lock removed. The carrier will not disclose those details to you as a third party.

If you previously had a different carrier or are looking to switch carriers, then you can contact your previous carrier to unlock the device as you were their customer and getting the unlock details does not violate anyone else's privacy.

Ask the wireless carrier involved if they'll unlock it, or visit their website. Apple won't do this unless they accidentally replaced an unlocked unit with a locked one, and nobody else can.

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