Huawei M931 User Manual page 110

Hearing Aid Compatibility (HAC) regulations for Mobile
phones
In 2003, the FCC adopted rules to make digital wireless
telephones compatible with hearing aids and cochlear implants.
Although analog wireless phones do not usually cause
interference with hearing aids or cochlear implants, digital
wireless phones sometimes do because of electromagnetic
energy emitted by the phone's antenna, backlight, or other
components.
Your phone is compliant with FCC HAC regulations (ANSI
C63.19).
While some wireless phones are used near some hearing
devices (hearing aids and cochlear implants), users may detect
a buzzing, humming, or whining noise.
Some hearing devices are more immune than others to this
interference noise, and phones also vary in the amount of
interference they generate.
The wireless telephone industry has developed a rating system
for wireless phones, to assist hearing device users find phones
that may be compatible with their hearing devices. Not all
phones have been rated. Phones that are rated have the rating
on their box or a label located on the box. The ratings are not
guarantees. Results will vary depending on the user's hearing
device and hearing loss. If your hearing device happens to be
vulnerable to interference, you may not be able to use a rated
phone successfully. Trying out the phone with your hearing
device is the best way to evaluate it for your personal needs.
M-Ratings: Phones rated M3 or M4 meet FCC requirements
and are likely to generate less interference to hearing devices
than phones that are not labeled.
M4 is the better/higher of the two ratings.
T-Ratings: Phones rated T3 or T4 meet FCC requirements and
are likely to be more usable with a hearing device's telecoil ("T
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