Today's is just that and it was added thanks to my buddy Wes.
It appears in 1994 Upper Deck released some phone cards with Sprint. Each of these are serial numbered (forgot to take a picture of the back for this post) and match the base card photo and design for the 1994 Upper Deck base set.
I didn't even know the phone card sports cards existed til 1995 with Pro Line. I guess they do.
Have you ever come across a card that you didn't know existed?