Campground availability in Yellow Stone NP

[Gjac]

I found a web site that shows what time the CG's inside the park fill up. We are leaving this Friday. Is there a telephone number that you can call when you get close to the park to see what sites are available? I see that some sites are still first come first served is there a separate phone number for these CG's?

[Us_out_West]

Isn't there a phone # on the website?