FaceTime RTT phone call requirements

If you have difficulties hearing or speaking or want to call someone who does, you can use Real-Time Text (RTT) for your phone calls, if your carrier supports it.

To make or receive an RTT call, make sure of the following:

• Your Mac has macOS 10.4.2 or later installed.

• Your iPhone has iOS 12.1.1 or later installed. See the Apple Support article Update your iPhone or iPad.

• Your iPhone and Mac are on the same Wi-Fi network and connected to the internet.

• You’re signed in with the same Apple ID on your Mac and iPhone. See the Apple Support article Use Continuity to connect your Mac, iPhone, iPad and Apple Watch.

• Your iPhone and Mac have Wi-Fi Calling turned on. Wi-Fi Calling isn’t available on some Mac models.

This feature isn’t available in all countries or regions or supported by all service providers. Depending on your network environment, an RTT call may be downgraded to a TTY call.