What are real-time text (RTT) and teletype (TTY)? How do I enable them?

RTT and TTY are protocols that transmit text in real time as you type, and allows the recipient to read and respond in real time as well. RTT/TTY software is built into the Phone app, so no additional equipment is needed, but your iPhone will also support the use of an external TTY device via the iPhone TTY Adapter (may be sold separately).

• Note: RTT and TTY are not supported by all carriers or in all countries or regions, and Apple does not guarantee that the operator will be able to receive or respond to an RTT or TTY emergency call placed in the United States. If you are unable to make and/or receive RTT calls on your handset, please contact Customer Support.

To turn on RTT and TTY, follow these steps:

1. From the main screen, tap the "Settings" icon.
2. Locate and tap "Accessibility."
3. Locate and tap "RTT/TTY" or "TTY." Then, tap and adjust the following options:
   • If your iPhone has Dual SIM capability, tap the desired line.
   • Tap"Software RTT/TTY" or "Software TTY."
     • Tap "Relay Number." Then, enter the phone number to use for relay calls using Software RTT/TTY.
     • Tap "Send Immediately" toggle this feature on/off. When "Send Immediately" is enabled, characters will be visible to the recipient as you type. Otherwise, you will need to complete the message before it will be sent to the recipient.
     • Tap "Answer All Calls as RTT/TTY" to toggle this option on/off. When "Answer All Calls as RTT/TTY" is enabled, call audio will not be heard during TTY calls.
     • Tap "Hardware TTY" to toggle this feature on/off. When "Hardware TTY" is enabled, you can connect an external TTY device to your iPhone. When both software and hardware TTY options are enabled, your calls will default to the hardware TTY device when it is connected to your iPhone.