Google Adwords and including your phone number

I've set up a new AdWords account and can include your phone number in the ad. The Google Adwords hotline is closed on the weekend. I ask you here.

If a user does not click on the ad and calls the number, how does Google track and calculate the AdWords user?

Another thing: I already get a call at least once a week from sellers trying to sell me a mostly useless or overpriced product (real estate). I think adding my phone number could lead to more sales.

Any feedback from Adwords users?