LG Envoy Owner's Manual page 113

"Normal usage" in this context is
defined as a signal quality that is
acceptable for normal operation.
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
components must be disabled
during a call. See Page 78 for
instructions to disable these
components.
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