2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)

11B-217.4.7 Transportation facilities.

In transportation facilities, in addition to the requirements of Sections 11B-217.4.1 through 11B-217.4.4, where at least one public pay telephone serves a particular entrance to a bus or rail facility, at least one public TTY shall be provided to serve that entrance. In airports, in addition to the requirements of Sections 11B-217.4.1 through 11B-217.4.4, where four or more public pay telephones are located in a terminal outside the security areas, a concourse within the security areas, or a baggage claim area in a terminal, at least one public TTY shall be provided in each location.