AT&T Cor DF transaction on credit card

My wife ordered 2 phones at the AT&T store on Monday. A shipping hold was placed on one because of the credit card on file having expired. She paid the taxes with a credit card other than the one on file and was told the activation fee would be charged to our next bill. Today, Wednesday, I updated the expiration date and shortly after got hit with a $72 charge from "AT&T COR Df". Can someone please help me understand what this charge is?