Huawei Mobile Phones User Manual page 24

Caution
Changes or modifications made to this device not expressly approved
by Huawei Technologies Co., Ltd. may void the FCC authorization to
operate this device.
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 Switch" or "Telephone
Switch") than unrated phones. T4 is the better/higher of the two ratings.
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