puk code

I just received a chromebook device for school from a non-profit organization program and I was trying to use my mobile data but I  made a mistake and locked it and I dont know the code it's asking for a Puk code the packaging and the sim card doesn't come with one so Im asking because it says my carrier can provide it for me and it sas on the sim card holder that all of the chrome books are from AT&T 

SKU: 6818B

UPC: 6 07376 82692 2
ICCID: 89012803320072762826