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What does TTY mean on a phone and how to use it

Learn to leverage this essential text-over-call feature.

Published onJanuary 4, 2024

Let’s look at one of the unsung heroes of phone accessibility, TTY mode. This feature, tucked away in your phone settings, allows individuals with hearing or speech impairments to communicate through text over regular phone calls. Here’s everything you need to know about what TTY means and how to set it up on Android and iPhone devices.


TTY, short for "teletypewriter," was originally designed to facilitate communication for individuals with hearing or speech difficulties by transmitting typed text over regular telephone lines. In today's smartphones, TTY mode mimics this feature, allowing text-based communication alongside voice calls


What is TTY Mode on your phone?

TTY stands for “teletypewriter.” It was initially developed for people with hearing or speech difficulties to communicate over traditional telephone networks. TTY devices translate typed text into electronic signals sent across the telephone network and retranslated to text at the other end.

Modern smartphones have an integrated TTY mode that works in the same way, allowing text communication over a voice call. When TTY mode is enabled, the phone will connect with a TTY device through a TTY cable. The person on the other end can read the message on their device’s display whether they’re using a TTY device or another phone with TTY mode.

TTY mode includes several settings: TTY Full, TTY HCO (Hearing Carry Over), and TTY VCO (Voice Carry Over). TTY Full allows for text-only communication, while TTY HCO and VCO allow for a combination of voice and text, catering to those who can speak but not hear and vice versa.

How to set up and use TTY on Android

Using TTY mode on Android devices is a little hard to find unless you search for “TTY” in Settings.

  • Instead of going to your Settings, open your Phone app.
  • Select Call Settings.
  • Scroll down and select Other call settings.
  • Scroll down and tap on TTY mode or Text telephone (TTY) mode, depending on your Android version.
  • Select the TTY mode you want to use—TTY Full, TTY HCO, or TTY VCO—based on your needs.

Once you’ve set up TTY mode, you can call usually. The text you or the other party types will appear on your connected TTY device’s display.

How to set up and use TTY on iPhone

iPhone users also have the TTY feature integrated into their devices. Follow these steps to set up and use TTY:

  • Open the Settings app.
  • Scroll down and tap on Accessibility.
  • Under the HEARING section, select TTY.
  • Toggle on Software TTY.

When you make a call, you’ll see an RTT button next to the contact’s name. Tap this button to start the RTT call. Type your message, and it will appear on the TTY device connected at the other end.


TTY in texting refers to the use of a teletypewriter mode in a mobile device, which allows users to type messages and send them as electronic signals over telephone lines, usually designed for individuals with hearing or speech impairments.

In phone calls, TTY stands for teletypewriter, a device or functionality that allows users to communicate via typed text rather than speech. This is especially helpful for people with hearing or speech impairments as the typed text is converted to electronic signals, transmitted over the phone line, and reconverted to text at the other end.

To use TTY when you call, you first need to connect your phone to a TTY device using a TTY cable or adapter. Once this is done, enable the TTY mode in your phone’s settings (usually under the Accessibility section). You can then make a phone call as usual, and the text you type will appear on the connected TTY device’s display.

A TTY call doesn’t “sound” like a typical phone call. Since the communication happens through text transmitted over the phone line, there’s typically no audible speech involved unless the TTY mode is set to HCO (Hearing Carry Over) or VCO (Voice Carry Over), which allows for a combination of voice and text.

Yes, even if you’re not deaf or hard of hearing, you can still use TTY mode if you have a TTY device. However, the primary purpose of TTY is to aid individuals with hearing or speech impairments, so they can communicate via phone calls more effectively.

No, TTY is not the same as a text message. While both involve typed text, a text message is sent via data or cellular network to another mobile device. TTY, on the other hand, is designed to work over voice phone lines and requires a TTY device or a smartphone with TTY mode to send and receive text-based communications during a call.

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