Sharp AQUOS Crystal Sprint User Manual page 322

2. Touch Call > TTY mode.
3. Touch TTY Full, TTY HCO, or TTY VCO to turn TTY mode on.
– or –
Touch TTY Off to turn TTY mode off.
 Your phone's TTY mode is set.
Note: When enabled, TTY mode may impair the audio quality of non-TTY devices connected to the
headset jack.
Warning: 9-1-1 Emergency Calling
It is recommended that TTY users make emergency calls by other means, including Telecommunications
Settings 312