7-11.1 Rationale

Services such as closed captioning and video description provide access to multimedia transmission for people with disabilities (see Chapter 8, Video and Multimedia). The information communicated through these services includes text, audio, and coded information for delivery and/or display of the information. This telecommunications product provision was created largely in response to problems with transmission of closed captioning information being distorted or removed - due to transmission problems - but it also applies to TTY tones (which are covered specifically in other telecommunications product provisions as well).

Historical sources of problems have been stripping and garbling or loss of synchronization of caption data due to compression, duplication, transmission, frame loss or removal, re–encoding, or digital rights management methods. Some systems completely remove captioning accidentally during transmission or compression simply because the designers are not aware that it exists in the synchronization, periods of the signal. On other systems, compression techniques may corrupt the captions, because the compression techniques were designed without knowledge of or consideration for captions. Still other systems, to save bandwidth, do not deliver secondary or auxiliary channels that carry accessibility information. Thus, the captioning or video description information is blocked, and the users who rely on these services for accessibility are denied their benefit.

Another example of TTY problems with digital service is in wireless (e.g., cellular) communications. In some systems, frame errors occur at levels that are tolerated well for voice communications, but are very disruptive to TTY communication. Other problems have arisen from some noise–cancellation algorithms in codecs and from some implementations of digital signaling and audio signal compression schemes. However, the wireless industry, under order from the FCC to make services compatible with TTYs, has now completed its work (in collaboration with handset and TTY manufacturers). Wireless carriers have reported to the FCC that their services carry TTY signals intact.

This provision applies to products and systems that transmit or conduct information or communications - regardless of format - that may contain coding necessary for accessibility (e.g., captioning information or video description in video transmissions). It would also apply to any other devices that transmit information or encode information for transmission (and decode it after). This provision also clearly applies to TTY signals passed through office telecommunications products and services (e.g., routers). TTYs were designed to function as modems over standard telephone lines. Some technological changes in telecommunications systems have caused problems for the TTY signals. This provision is written broadly so as to cover future telecommunications services that may affect accessibility. Captioning, video description, and TTY products that meet the criterion of “cross–manufacturer, non–proprietary, industry–standard” should be supported.

Telecommunications is defined as “the transmission, between or among points specified by the user, of information of the user's choosing, without change in the form or content of the information as sent and received.”

This definition is used extensively in law and regulations affecting telecommunications products. Therefore, there exists substantial legislative, regulatory, and case history defining its terms and scope.