How To Track Phone Calls from a Site? - bounce house games

I built a relatively small website for the local small niche (bounce house rental.
It receives about 700 visitors a month.
This is a very high conversion niche because people only need a number to quote and book one if the price sounds right.
I don't know anything about the industry and I want to rent it to someone who is already in the industry but has a crappy website that doesn't have traffic every month.
In order to assess the value of the site, I need to know how many of these "clicks" actually convert to phone inquiries.
Assuming the price is competitive, I'm assuming that in this area people who actually pick up the phone to check availability will have a 80% conversion rate.
I may be completely wrong, though.
Is there a system where I can set up a phone number that redirects to another phone number of my choice, but I can collect statistics on the published number?
In this way, I can understand the number of calls and the rough value of the website to the business people.