811 Know what's below. e Call before you dig. To locate and mark buried utility gas, electric, cable and telephone lines, call 811 at least two business days before digging begins. It's safe, it's free and it's the law. ATMOS energy. If you suspect a natural gas leak, leave the area immediately, and then call 911 and 1-866-322-8667. For more information about gas safety, visit www.atmosenergy.com.