Real-Time Text is text transmitted instantly as it is being typed or created.
Recipients can immediately read the message while it is being written,
RTT is more dynamic and interactive than "regular" texting. RTT can still be done on cell phones, but two conversation boxes are displayed on the screen, one for each user. One person types a message, while at the same time the other person sees the words forming, letter by letter, in one of the text boxes. In the other box, you can write responses, ask questions, and even interrupt, all at the same time.
Real Time Text makes it possible for the hearing or speech impaired to participate in natural, direct conversations that are a lot like verbal conversations :-)