Samsung Galaxy S III - Launching an Installed Google Application; Unknown sources; Manage applications

To turn TTY Mode on or off:
1.
From home, tap Apps
> Settings > My device tab > Call.
2. Tap TTY mode.
3. Tap TTY Full, TTY HCO, or TTY VCO to turn TTY mode on.
– or –
Tap TTY Off to turn TTY mode off.
 Your phone’s TTY mode is set.
Settings 271