Motorola KRZR K1m Owner's Manual page 43

option
HCO
Transmit TTY characters but receive by
listening to earpiece.
When your phone is in a TTY mode, the
international TTY mode, the international TTY
symbol, and the mode setting display during
an active TTY call.
return to voice mode
To return to standard voice mode, select Voice
from the TTY Setup menu.
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