Samsung Galaxy S8 / S8+ - Manage TTY Settings
- From a Home screen, tap the Phone icon
(lower-left).
If unavailable, touch and swipe up or down then tap Phone . - Tap the Menu icon
(upper-right) then tap Settings. - Tap Other call settings.
- Tap TTY mode then select one of the following:
- TTY OFF: Disables all TTY settings
- TTY FULL: Enables all TTY settings
- TTY HCO: Enables HCO (Hearing Carry Over)
- TTY VCO: Enables VCO (Voice Carry Over)
(lower-left).
If unavailable, touch and swipe up or down then tap Phone 
(upper-right) then tap Settings.