Set up and use TTY or RTT on iPhone
If you have hearing or speech difficulties, you can communicate by telephone using Teletype (TTY) or real-time text (RTT)—protocols that transmit text as you type and allow the recipient to read the message right away. RTT is a more advanced protocol that transmits audio as you type text.
iPhone provides built-in Software RTT and TTY from the Phone app—it requires no additional devices. If you turn on Software RTT/TTY, iPhone defaults to the RTT protocol whenever it’s supported by the carrier.
iPhone also supports Hardware TTY, so you can connect iPhone to an external TTY device with the iPhone TTY Adapter (sold separately in many regions).
Important: RTT and TTY aren’t supported by all carriers or in all regions. RTT and TTY functionality depends on your carrier and network environment. When making an emergency call in the U.S., iPhone sends special characters or tones to alert the operator. The operator’s ability to receive or respond to these tones can vary depending on your location. Apple doesn’t guarantee that the operator will be able to receive or respond to an RTT or TTY call.
Set up RTT or TTY
Go to Settings > General > Accessibility.
Tap RTT/TTY or TTY, then do any of the following:
If your iPhone has Dual SIM, choose a line.
Turn on Software RTT/TTY or Software TTY.
Tap Relay Number, then enter the phone number to use for relay calls using Software RTT/TTY.
Turn on Send Immediately to send each character as you type. Turn off to complete messages before sending.
Turn on Answer All Calls as RTT/TTY.
Turn on Hardware TTY.
When RTT or TTY is turned on, appears in the status bar at the top of the screen.
Connect iPhone to an external TTY device
If you turned on Hardware TTY in Settings, connect iPhone to your TTY device using the iPhone TTY Adapter. If Software TTY is also turned on, incoming calls default to Hardware TTY. For information about using a particular TTY device, see the documentation that came with it.
Start an RTT or TTY call
In the Phone app, choose a contact, then tap the phone number.
Choose RTT/TTY Call or RTT/TTY Relay Call.
Wait for the call to connect, then tap RTT/TTY.
iPhone defaults to the RTT protocol whenever it’s supported by the carrier.
If you haven’t turned RTT on and you receive an incoming RTT call, tap the RTT button to answer the call with RTT.
Type text during an RTT or TTY call
Enter your message in the text field.
If you turned on Send Immediately in Settings, your recipient sees each character as you type. Otherwise, tap to send the message.
To also transmit audio, tap .
Review the transcript of a Software RTT or TTY call
In the Phone app, tap Recents.
RTT and TTY calls have next to them.
Next to the call you want to review, tap .
Note: Continuity features aren’t available for RTT and TTY support. Standard voice call rates apply for both Software RTT/TTY and Hardware TTY calls.