Texttelefonie

Texttelefonie, also known as teksttelefonie or teletypewriter communication, is a method of telephone communication designed for people who are deaf, hard of hearing, or speech-impaired. It uses a text-based device connected to the telephone network to type and read messages in real time, allowing conversations to take place without vocal speech.

Traditionally, texttelefonie involved TTY terminals connected to a telephone line via a modem or acoustic coupler, transmitting typed characters as tones and displaying received text on a screen or printer. Today, many users rely on computer or smartphone apps, USB or Bluetooth adapters, and Voice over IP (VoIP) or mobile networks to achieve similar functionality. Some setups still work in pairs of TTY devices, while others use a telecommunication relay service.

Relay services are common in many countries and provide accessibility when one party does not have a compatible device. A trained operator types the conversation for the hearing person and vocalizes or otherwise conveys the other party’s spoken responses, then types the reply back. Regulations and standards often require the provision of such services to ensure equal access to telephone communication.

Real-time text (RTT) over digital networks represents a modern evolution of texttelefonie, allowing immediate text transmission during calls without separate hardware. While the use of traditional TTY devices has declined with widespread digital communication, texttelefonie remains a valuable accessibility option for individuals who rely on text-based communication on the telephone.

See also: TTY, RTT, telecommunication relay service, accessibility.