47 CFR 68.300 - Labeling requirements.
(a) Terminal equipment approved as set out in this part must be labeled in accordance with the requirements published by the Administrative Council for Terminal Attachments and with requirements of this part for hearing aid compatibility and volume control.
(b) As of April 1, 1997, all registered telephones, including cordless telephones, as defined in § 15.3(j) of this chapter, manufactured in the United States (other than for export) or imported for use in the United States, that are hearing aid compatible, as defined in § 68.316, shall have the letters “HAC” permanently affixed thereto. “Permanently affixed” shall be defined as in paragraph (b)(5) of this section. Telephones used with public mobile services or private radio services, and secure telephones, as defined by § 68.3, are exempt from this requirement.