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 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.
To enter that the Hearing Aid Compatibility rating for your phone is maintained, secondary transmitters such as Bluetooth and WLAN components must be disabled during a call.
For information about hearing aids and digital wireless phones
Wireless Phones and Hearing Aid Accessibility http://www. accesswireless.org/
FCC Hearing Aid Compatibility and Volume Control http://www. fcc.gov/cgb/consumerfacts/hac_wireless.html
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