TDD Phone Vs. Texting

Communicating via TDD and texting are similar in some ways, quite different in others..

A telecommunications device for the deaf, also known as a TDD device, give deaf or hard-of-hearing users the ability to use telephones, including mobile phones, by typing conversations instead of speaking them. Conversations carried on using TDD-equipped devices require at least one device to have the feature and involves a moderator. Texting, on the other hand, is similar to TDD but does not involve a moderator and can take place between devices that are designed to send and receive text messages.

Basics

Sending and receiving text messages via mobile phone is sufficient for hard-of-hearing and deaf users to communicate with each other and does not require the use of the TDD feature. Mobile phones that come with the TDD functionality are designed primarily to help deaf and hard-of-hearing users communicate with those who are not deaf or hard-of-hearing. TDD-equipped phones can place calls to and receive calls from phones that do not feature the service, but must first contact a Telecommunications Relay Service to do so.

Processes

Conversations using text messages are sent directly from one device to another. Phone conversations that involve the use of TDD are mediated by a TRS operator, who remains connected to the phone call to relay TDD and verbal messages between the parties. TRS centers are offered in each state, are open 24 hours a day and have no restrictions on call lengths or the amount of calls that can be placed. Text messages are also available 24 hours a day, but are limited in length to 160 characters and can involve message receiving delays, which can result if one party is out of range or has turned off his phone.

Technology

TDD functionality involves contacting a land-based phone line -- the TRS -- to converse with another party, while text messages, also known as Short Message Service protocol, are sent wirelessly through a wireless provider’s network. TDD can also connect with computers that are capable of using the American Standard Code for Information Interchange technology on the computer’s end and the Baudot code technology on the phone’s end. ASCII-equipped computers are capable of receiving calls from TDD-equipped phones, including mobile phones. Similarly, text messages can also be sent to a computer by addressing the text message to an email address.

Miscellaneous

Text messages can be sent from one device to another by addressing the message to any email address or 10-digit wireless phone number. The TDD feature on a mobile phone, on the other hand, must be activated before it can be used.

References

• Adco Hearing Products, Inc.: What Is TTY?
• Phone Scoop Glossary: SMS