Sprint unlocked my Galaxy S6. I insert a China mobile sim card (gsm). The phone shows "invalid sim card". I even cannot find network setting or APN setting now.
The same sim card works for other phones (iphone5, iphone 6).
I called Sprint and was told Sprint has unlocked it and nothing else to do.
I went to a Sprint repair center and was told the same thing.
The clerk reboot to factory setting with the same error.
Have you checked with the new carrier to make sure the S6 is compatible. Not all phones are.
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