Text telephone devices (TTYs or TDDs) are used by people with hearing or speech disabilities to send and receive text messages over telephone networks. In the past, wireline telephone and analog cellular networks generally were compatible with TTYs, but digital wireless networks were not. As a result of FCC rules to ensure that TTY users can complete emergency 911 calls, wireless service providers have upgraded their digital networks to be compatible with TTYs. Consumers are now generally able to use TTYs to complete calls with their digital wireless phones, including 911 calls, if the phone itself is TTY-compatible. To find a TTY-compatible digital wireless phone, contact your wireless service provider or handset retailer.