47 CFR § 95.1733 - Prohibited GMRS uses.
(1) Messages in connection with any activity which is against Federal, State, or local law;
(2) False or deceptive messages;
(3) Coded messages or messages with hidden meanings (“10 codes” are permissible);
(4) Music, whistling, sound effects or material to amuse or entertain;
(5) Advertisements or offers for the sale of goods or services;
(6) Advertisements for a political candidate or political campaign (messages about the campaign business may be communicated);
(7) International distress signals, such as the word “Mayday” (except when on a ship, aircraft or other vehicle in immediate danger to ask for help);
(9) Messages (except emergency messages) to any station in the Amateur Radio Service, to any unauthorized station, or to any foreign station;
(10) Continuous or uninterrupted transmissions, except for communications involving the immediate safety of life or property; and
(11) Messages for public address systems.
(12) The provision of § 95.333 apply, however, if the licensee is a corporation and the license so indicates, it may use its GMRS system to furnish non-profit radio communication service to its parent corporation, to another subsidiary of the same parent, or to its own subsidiary.
(b)GMRS stations must not be used for one-way communications other than those listed in § 95.1731(b). Initial transmissions to establish two-way communications and data transmissions listed in § 95.1731(d) are not considered to be one-way communications for the purposes of this section.