Samsung Galaxy J3 User Manual page 88

Apps
Real Time Text (RTT)
Type back and forth in real time with the other person while on a call.
You can use RTT whenever you are calling someone whose phone also supports RTT or
is connected to a teletypewriter (TTY) device. The RTT icon appears on all incoming
RTT calls.
1. From Phone, tap
2. Tap Real time text for the following options:
• Always visible: Show the RTT call button on the keypad and during calls.
• Use external TTY keyboard: Hide the RTT keyboard when an external
TTY keyboard is connected.
• TTY mode: Choose the preferred TTY mode for the keyboard in use.
NOTE To use RTT, you must be connected to a 4G LTE or Wi-Fi network.
More options > Settings.
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