User's Manual

of digital wireless phones with hearing aids is set forth in
American National Standard Institute (ANSI) standard
C63.19. There are two sets of ANSI standards with ratings
from one to four (four being the best rating): an “M” rating
for reduced interference making it easier to hear
conversations on the phone when using the hearing aid
microphone, and a “T”
rating that enables the phone to be used with hearing aids
operating in the tele-coil mode thus reducing unwanted
background noise.