47 CFR § 5.504 - Responsible party.
Compliance testing licensees must identify a single point of contact responsible for all experiments conducted under the license, including ensuring compliance with all applicable FCC rules:
(a) The responsible individual will serve as the initial point of contact for all matters involving interference resolution and must have the authority to discontinue any and all experiments being conducted under the license, if necessary.
(b) The name of the responsible individual, along with contact information, such as a phone number and email address at which he or she can be reached at any time of the day, must be identified on the license application, and this information will be listed on the license. Licensees are required to keep this information current.