47 CFR 1.951: Duty to respond to official communications.

Licensees or applicants in the Wireless Radio Services receiving official notice of an apparent or actual violation of a federal statute, international agreement, Executive Order, or regulation pertaining to communications shall respond in writing within 10 days to the office of the FCC originating the notice, unless otherwise specified. Responses to official communications must be complete and self-contained without reference to other communications unless copies of such other communications are attached to the response. Licensees or applicants may respond via ULS.