Real-time Text (RTT) is a text service that carriers provide in certain countries/regions. It allows each character in a message to be read as it is typed. Check with your carrier to learn whether RTT is available with your service plan. Please note that in order to contact 911 using RTT in the United States, your phone must have a SIM card installed. For more information about using RTT on your phone, please visit https://support.google.com/accessibility/android.