Samsung SGH-t309 - Manual (Page 174)

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hearing devices. Not all phones have been rated. Phones
that are rated have the rating on their box or a label 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. (Note
that not all hearing devices have telecoils in them.)
Hearing devices may also be measured for immunity to
this type of interference. Your hearing device
manufacturer or hearing health professional may help
you find results for your hearing device. The more
immune your hearing aid is, the less likely you are to
experience interference noise from mobile phones.
Other Medical Devices
If you use any other personal medical devices, consult the
manufacturer of your device to determine if it is
adequately shielded from external RF energy. Your
physician may be able to assist you in obtaining this