47 CFR § 64.201 - Restrictions on indecent telephone message services.
(a) It is a defense to prosecution for the provision of indecent communications under section 223(b)(2) of the Communications Act of 1934, as amended (the Act), 47 U.S.C. 223(b)(2), that the defendant has taken the action set forth in paragraph (a)(1) of this section and, in addition, has complied with the following: Taken one of the actions set forth in paragraphs (a)(2), (3), or (4) of this section to restrict access to prohibited communications to persons eighteen years of age or older, and has additionally complied with paragraph (a)(5) of this section, where applicable:
(1) Has notified the common carrier identified in section 223(c)(1) of the Act, in writing, that he or she is providing the kind of service described in section 223(b)(2) of the Act.
(2) Requires payment by credit card before transmission of the message; or
(3) Requires an authorized access or identification code before transmission of the message, and where the defendant has:
(i) Issued the code by mailing it to the applicant after reasonably ascertaining through receipt of a written application that the applicant is not under eighteen years of age; and
(ii) Established a procedure to cancel immediately the code of any person upon written, telephonic or other notice to the defendant's business office that such code has been lost, stolen, or used by a person or persons under the age of eighteen, or that such code is no longer desired; or
(4) Scrambles the message using any technique that renders the audio unintelligible and incomprehensible to the calling party unless that party uses a descrambler; and,
(5) Where the defendant is a message sponsor subscriber to mass announcement services tariffed at this Commission and such defendant prior to the transmission of the message has requested in writing to the carrier providing the public announcement service that calls to this message service be subject to billing notification as an adult telephone message service.
(b) A common carrier within the District of Columbia or within any State, or in interstate or foreign commerce, shall not, to the extent technically feasible, provide access to a communication described in section 223(b) of the Act from the telephone of any subscriber who has not previously requested in writing the carrier to provide access to such communication if the carrier collects from subscribers an identifiable charge for such communication that the carrier remits, in whole or in part, to the provider of such communication.