They will return your call if you are making a reservation. 8f your just visiting, just drive in.
It depends on what you plan to do in the canyon. If its just a day visit, no resv is needed. But if you plan to stay overnight to camp, or to backpack or rock climb you'll need resv's...if you leave a msg they should call you back within a day or two
Thanks! Your answer is awaiting moderation.