Samsung SM-G780G/DS User Manual page 45

Apps and features
Communicating by typing text
If your voice is not recognized due to noisy environments or if you are in a situation where
speaking is difficult, you can communicate with Bixby via text.
Launch the Bixby app, tap , and then type what you want.
During the communication, Bixby also will answer you through text instead of voice
feedback.
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