Which item is necessary for individuals to communicate via text telephone devices?

To communicate using text telephone devices, it is essential to have a Text Telephone Device, commonly referred to as a TTY or TDD. This device is specifically designed to enable individuals, particularly those who are deaf or hard of hearing, to send and receive text messages over a phone line.

The Text Telephone Device converts typed text into signals that can be transmitted over the telephone network, allowing for real-time text communication between users. Without this device, individuals would not have the capability to communicate using text on a phone line, as standard telephones are designed primarily for voice communication.

Other options, such as specialized training or a regular telephone, may be beneficial in certain contexts but do not provide the fundamental capability needed for text-based communication. An electric connection is necessary for all electrical devices, but it does not specifically address the unique requirements for text telephony. Thus, a Text Telephone Device is the indispensable item needed for this form of communication.