Google Adwords and including your phone number

[H2 rider]

I setup a new adwords account and an option is to include your phone number in the ad. Google Adwords help line is closed on the weekend so I'll ask here.

If a user doesn't click on the ad and calls the number, how does Google track and charge the adwords user?

Another thing - I already get at least one call per week from salespersons trying to sell me what is usually a useless or overpriced product related to my business (real estate). I'm thinking adding my phone number might just result in more sales calls.

Any feedback from Adwords users?

[H2 rider]

I called Adwords and got the answer. They assign their own dedicated phone number for customers to call which forwards to your phone.