We Tell You What is the TTY Mode on Cell Phones and How to Use it

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What is the TTY Mode on Cell Phones and How to Use it?

The TTY mode helps the hearing and speech-impaired to communicate over phone lines. We tell you about this mode and help you know how to use it.

Did You Know?

According to the Title IV of the Americans with Disabilities Act, the TTY service should be extended free of charge by every state.

TTY (short for teletypewriter), also known as telecommunication device for the deaf (TDD) or text telephone, is a term used for devices that are meant for sending texts over phone lines. It allows text messages to be sent and received synchronously. Written communication over phone lines proves to be of great use to those hard of hearing, the deaf, and the speech-impaired.

To switch to the TTY mode, the phone is connected to a TTY device that can transcribe written messages into voice notes and vice versa, according to your preference.

What is TTY?

TTY enables a person to type messages which are displayed on the receiver’s phone screen, without much delay or loss of connection. This feature enables the speech and hearing-impaired people to communicate over phone. When a TTY device is connected to a cell phone, it starts sending and/or receiving written messages. For this mode of communication to be possible, both the (sender and receiver) phones should be enabled with the TTY mode.


VCO stands for ‘voice carry over’. This feature is meant for people who are able to talk but are hearing-impaired. A hearing-impaired person can communicate verbally but needs to be sent typed messages. This is enabled by TTY VCO.


HCO stands for ‘hearing carry over’. This feature is designed for those who can hear clearly but are unable to speak. The person who is unable to speak, can listen to messages but needs to send typed messages over the phone line. This is facilitated by TTY HCO.


  • A TTY device has a keyboard and a screen. There are two types of TTY devices. One has a built-in phone whereas the other one has to be connected to a phone. Here, we shall discuss the latter.
  • Cell phones, individually, are not TTY devices. A TTY device has to be connected to the cell phone with a cable. One end of this cable should be plugged into the cell phone’s headset jack and the other end into the TTY device. This cable works as an audio-in, and audio-out connector.
  • Only when a cell phone is in the TTY mode, it is compatible with a TTY device.
  • The TTY device encodes data (messages or voice notes) which have to be sent, and thereby, transmits them through a modem. The TTY device on the other end (receiving end), decodes these messages to display them on the screen.


Find the TTY option in the ‘Settings’ of your phone and proceed as follows.

On iPhone

  • Select the ‘Settings’ option and choose ‘Phone’.
  • Turn on the TTY mode by moving the slider to ‘On’ position.
  • With an audio jack or adapter, connect the iPhone and the TTY device.
  • Now, you are ready to communicate.

On LG Android Mobile Phone

  • Go to ‘Settings’ and select ‘System settings’.
  • Then choose ‘Call’. Here, you will see the TTY option.
  • You will need to choose from a list of options which include TTY Off, TTY Full, TTY HCO, and TTY VCO.
  • According to your requirement, choose from the above options, by turning the necessary option ‘On’.

On Samsung Galaxy

  • Go to ‘Settings’. Select ‘My Device’.
  • Then choose, ‘Call’. Here, you will find the option ‘TTY mode’.
  • When you select the TTY mode, you will have an option to choose from TTY Off, TTY Full, TTY HCO, and TTY VCO.

According to the Federal Law of America, people who are speech and hearing-impaired, deserve to be able to communicate as definitely as possible. TTY has been introduced with the thought of providing this section of people, with an easy means of communication over phones.

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