Direct quote from their 'contact us' page... "...Phone-based customer support is not offered at this time".
The phone number of the Mammoth Site is: 605-745-6017.
The phone number of the Oaklands Historic Site is: 615-893-0022.
The phone number of the Sandusky Historic Site is: 434-832-0162.
The phone number of the Sully Historic Site is: 703-437-1794.
The phone number of the Wade Historical Site is: 414-526-3271.
The phone number of the Pendarvis Historic Site is: 608-987-2122.
Phone numbers are not permitted on this site.
The site doesn't provide phone numbers.
The phone number of the Hampton National Historic Site is: 410-823-1309.
The phone number of the Hackley And Hume Historic Site is: 231-722-7578.
The phone number of the Jefferson College Historic Site is: 601-442-2901.
The phone number of the Mastodon State Historic Site is: 314-464-2976.