In 2005, my friends Dave and Adam built a pizza button in our dorm, it actually used the modem to send a fax to a local pizza place because that's all they had. Pushing the button ordered a cheese, but there were two auxiliary buttons underneath to select a topping via a Huffman code. (0 for pepperoni, 10 for sausage, 110 for anchovy, etc.)

I presume there are better APIs today :)