47 CFR §80.393

Automatic Identification Systems (AIS) are a maritime broadcast service. The simplex channels at 156.775 MHz (AIS 3), 156.825 MHz (AIS 4), 161.975 MHz (AIS 1), and 162.025 MHz (AIS 2), each with a 25 kHz bandwidth, may be authorized only for AIS. In accordance with the Maritime Transportation Security Act, the United States Coast Guard regulates AIS carriage requirements for non-Federal Government ships. These requirements are codified at 33 CFR 164.46, 401.20.