RTT or Real-Time Text is a feature provided by mobile phone manufacturers mainly to help people with hearing and speech difficulties. The message that you type appears to the other end in real-time. The telecom carriers should allow the support to use it on your phone. There are situations where we have to use this feature. It can be used for passing an urgent message or communicating an important confidential matter. It can be used when you wanted to communicate with somebody in a noisy environment where a call is not possible. The sole factor to take into account in an RTT calling is the tariff charges by the carrier. Those with hearing and speech difficulties can type the message and involve in the conversation with others using TTY or RTT. TTY supports certain formats only, but RTT supports many International Language formats.