2010 California Standards for Accessible Design (excerpts relating to Safe Harbors only)

SECTION 1117B - OTHER BUILDING COMPONENTS

1117B.2 Telephones.

1117B.2.8 Telephone equipment for hearing impaired persons.  Telephones shall be equipped with a receiver that generates a magnetic field in the area of the receiver cap. All telephones required to be accessible shall be equipped with a
volume control. In addition, 25 percent, but never less than one, of all other public telephones provided shall be equipped with a
volume control and shall be dispersed among all types of public telephones, including closed circuit telephones, throughout the
building or facility. If banks of public telephones are provided, at least one in each bank shall be equipped with a volume control. Such telephones shall be capable of a minimum of 12 dBA
and a maximum of 18 dBA above normal. If an automatic reset
is provided, 18 dBA may be exceeded. Public telephones with
volume control shall be hearing aid compatible and shall be identified by a sign containing a depiction of a telephone handset with radiating sound waves.