49 CFR Parts 37 & 38 - Department of Transportation (DOT) ADA Regulations

For terminological clarity, we want to point out that two different words are used in ADA regulations to refer to devices on which individuals with hearing impairments communicate over telephone lines. DOJ uses the more traditional term "telecommunications device for the deaf" (TDD). The Access Board uses a newer term, "text telephone.'' The DOT rule uses the terms interchangeably.