What happens if you break a phone that's paid monthly?

So I have an iPhone 7 Plus that I pay $15/mo for, but I didn't think about the fact of what would happen if I broke it. Would I have to pay the rest of the $650 (retail price) up front? Or would they still charge me monthly on my bill?

Get square trade, it's about 1/2 of the other insurance plans:
https://www.squaretrade.com/smartphone-warranty

You could do either. However, the full cost of a replacement phone is on you.