Pretty sure the iPad could make/get phone calls? It was essentially just a charge for grouping it into my existing data/etc plan. $10 a month is definitely the price they're currently saying: https://www.macrumors.com/2017/09/12/lte-apple-watch-att-ver...

Fwiw, I am totally jumping on this. I'm not a big watch person, but the utility of leaving the phone home on date nights is going to be a huge win. This is a much bigger game changer than anything else they introduced