The M mark is intended to be
synonymous with the U mark.
The T mark is intended to be
synonymous with the UT mark.
The M and T marks are
recommended by the Alliance for
Telecommunications Industries
Solutions (ATIS). The U and UT
For information about hearing aids and digital wireless
phones
FCC Hearing Aid Compatibility and Volume Control
http://www.fcc.gov/cgb/dro/hearing.html
Gallaudet University, RERC
http://tap.Gallaudet.edu/DigWireless.KS/DigWireless.htm
Hearing Loss Association of America [HLAA]
http://www.hearingloss.org/learn/cellphonetech.asp
The Hearing Aid Compatibility FCC Order
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-03-
168A1.pdf
marks are referenced in Section
20.19 of the FCC Rules. The
HAC rating and measurement
procedure are described in the
American National Standards
Institute (ANSI) C63.19
standard.
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