AT&T Real-Time Text

Continue the conversation, wherever you are.  AT&T Real-Time Text (RTT) helps AT&T customers with disabilities communicate over the wireless network as an alternative to TTY (TeleTYpewriter). RTT uses a free-flowing mix of text and voice conversation, so as quickly as characters are typed on the sending device, they are displayed on the receiving device.  
RTT is a separate service from traditional text messaging (SMS).
–Great for everyday communication
–Supports 711 and 911 calls
–Eliminates the need to connect to mobile TTY devices
–Works on the AT&T cellular network and over Wi-Fi Calling
–Offers a more natural, conversational flow compared to TTY and relay service for persons who are deaf, hard-of-hearing, or have speech disabilities
–Supports simultaneous text and speech on RTT-to-RTT calls
–Automatically imports contacts from your phone
–Works on Android Smartphones and tablets operating system 4.4 and up; 

[1]Data and voice rates may apply for app download & usage.