When you turn on TTY (teletype) support and you connect your BlackBerry device to a TTY device that operates at 45.45 bps, you can make calls to and receive calls from TTY devices. Your BlackBerry device is designed to convert received calls to text that you can read on your TTY device.
Your TTY device must have an audio connector. If your TTY device is designed for use with a 2.5-mm headset jack, or if your TTY device has an RJ-11 connector (phone plug), you must use an adapter accessory to connect your TTY device to your BlackBerry device. To get an adapter accessory that BlackBerry has approved for use with your BlackBerry device, visit www.shopblackberry.com.
Depending on your wireless service provider or wireless coverage area, TTY support might not be available. This feature is not supported over a Wi-Fi connection. For more information, contact your wireless service provider.