Q: how to unlock with PUK code an iphone 6 with IOs 8.13

From this support document. iOS: Understanding the SIM PIN - Apple Support

Personal Unlocking Key (PUK)

If you enter the PIN incorrectly three times, you may need to enter a Personal Unlocking Key (PUK) to enable your SIM card again. Refer to the SIM card documentation or contact your carrier.

Note: Entering an incorrect PUK code too many times will result in the SIM becoming permanently locked. If this occurs, you will need to contact your carrier for a replacement SIM card.

You will need to get PUK information from your carrier. They have the SIM PUK

If you power the phone off and back on, does it enable a dialog box for you to enter the PUK? I've never experienced this before, I've always just seen documentation about clicking on unlock to enter the PUK or SIM PIN. I suggest that you check back with your carrier. Someone has obviously had to deal with this in the past.

You're welcome.

Hi, but the pin code is 4 digits and the PUK code is longer, my phone is locked and is asking for the pin code, how do I enter the longer PUK into the pin code area?