Zte Zmax User Manual page 168

Trying out the phone with your hearing device is the best way to evaluate
it for your personal needs.
This phone has been tested and rated for use with hearing aids for some
of the wireless technologies that it uses. However, there may be some
newer wireless technologies used in this phone that have not been tested
yet for use with hearing aids. It is important to try the different features of
this phone thoroughly and in different locations, using your hearing aid or
cochlear implant, to determine if you hear any interfering noise. Consult
your service provider or the manufacturer of this phone for information on
hearing aid compatibility. If you have questions about return or exchange
policies, consult your service provider or phone retailer.
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.
(Note that not all hearing devices have telecoils in them.)
Your phone meets the M4/T3 level rating.
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