A TTY, or teletypewriter, is a device used to help deaf people communicate. Many mobile phones today have the ability to connect to TTY devices, allowing hearing-impaired people to converse with others using a TTY device. When enabling or disabling TTY mode on your phone, certain elements of your phone become become unusable.
TTY devices are machines that are specifically designed to allow hearing and speech impaired people to communicate with one another over long distances. Because hearing- or speech-impaired people are unable to use telephones in the conventional way, the TTY machine displays text messages. Both parties require TTY devices to communicate with one another. If your cell phone has TTY capabilities, it can be connected to a TTY device, and you can communicate with someone else who has a TTY device. Unlike text messaging, TTY language and protocol is designed for instant communication. For instance, the term "GA," short for "go ahead," is used at the end of a sentence, signifying that it's the other person's turn to speak.
One of the main functions of TTY devices is the ability to connect to TRS, or the Telecommunications Relay Service. This service translates words into text, and text into words. Essentially, this allows a non-hearing-impaired person to speak into the telephone, and hear words being spoken back. On the other end, however, is a hearing-impaired person typing words, and seeing words being typed back to him. In the past, operators used to translate the communication, but today, human voice recognition software is being implemented to relay the communications between the two parties.
You can connect your mobile headset to a TTY device through the headphone jack, but you'll first need to enable TTY in your phone's settings. While each phone is different, you can usually find the TTY option under the "General Settings" menu. Choose to turn TTY on before connecting your phone to a TTY device. Enabling TTY mode may cause you to lose the ability to receive non-TTY calls and text messages. You may also be unable to open certain applications on smartphones.
Turning off TTY mode on your phone will allow you to use the normal non-TTY functions of your phone again, such as making and receiving basic phone calls and text messages. However, you will not be able to receive, or make, TTY phone calls. If you're expecting a TTY phone call, then you need to enable your TTY mode ahead of time. Other than not being able to receive TTY calls, there shouldn't be any other negative consequences of turning off TTY mode. Your phone should still function as normal.