Specialized CPE (SCPE) includes assistive technology devices that are capable of originating, terminating, or routing telecommunications calls. This category includes direct connect TTYs and environmental controls with a telephone function. It also includes some software designed as assistive technology that contain telecommunications functions. For the purposes of Section 255, it does not include typical communication aids for people with speech impairments. We have included that equipment in this Report because the people who use communication aids are interested in improving their access to telecommunications through their communication aids.
It is understood that manufacturers of SCPE are subject to Section 255 in the same way that manufacturers of regular CPE are. That is, it should be made accessible if readily achievable. This means, for example, that TTYs should be able to be used by people with low vision, with limited reach or strength, etc.
Many assistive devices do not have any telecommunications functions, even though those functions would seem to be natural extensions. Manufacturers may be reluctant to incorporate telecommunications features because their products would then become subject to FCC regulation. If this is the case, consumers are missing out on essential functions that manufacturers are able to and would like to provide. See Recommendation F2.
TTYs are the text terminals used by some people who are deaf, hard of hearing, or speech impaired to communicate over regular telephone lines. A TTY is normally used at both ends of the call. (Note: Voice users without a TTY communicate with TTY users through the Telecommunications Relay Service (TRS). In TRS an operator has both a voice phone and a TTY, and serves as a translator between the two end parties.)
TTYs consist of a keyboard, a single-line display, and a character encoder and decoder. (Note: One manufacturer offers a TTY with a two line display. This raises the issue of whether the two lines can be collapsed into one line with larger characters, making it more readable by people with low vision.) Direct connect TTYs can be plugged into a phone jack, for they contain the telephone line interface and dialing circuitry that allows them to function as CPE. They can make and receive calls independently. Other TTYs have an acoustic coupler into which a regular telephone handset is placed; these TTYs cannot place or receive calls by themselves. Some new TTYs have an audio jack to facilitate connection to wireless phones through the telephones’ 2.5 mm headset jack.
One model of TTY has braille input and output in addition
to a keyboard and visual display. This product may no longer be commercially
available but is still offered through some state equipment distribution programs.
TTYs use a 5-bit frequency shift keying code called Baudot that is not compatible with ASCII, the coding scheme used by computers. Baudot is half-duplex; only one person can type at a time. Baudot is relatively slow; its 45.45 baud is generally fast enough for typing but not for file downloading. This is rarely a problem, as TTYs are used for real-time conversation, like telephones, rather than for computer-style functions. In addition, Baudot, because it does not use a carrier tone to maintain the connection, allows users to mix voice and data on a call, or transfer a call between lines without trouble.
Some TTYs are available with an additional ASCII (300 baud) capability. Some TTY manufacturers are responding to consumer concerns about Baudot by developing different protocols, which allow greater speed and the ability to interrupt. However, these proprietary protocols serve to reduce interoperability, both with other TTYs and with TRS. In the long run, today’s TTYs are likely to be replaced by more advanced TTYs or by mainstream products with the features needed by TTY users. Interoperability with advanced mainstream services remains one of the key concerns of technology-aware TTY users. See Recommendation F5.
Direct connect TTYs can output DTMF tones for the purpose of dialing a call. However, many of these cannot send DTMF later in a call if needed for response to an audiotext/interactive voice response (IVR) or voice mal system. Some TTYs with a high line load may reduce the energy of touch-tones sent by a separate touch-tone phone on the same line, causing difficulty interacting with IVR systems.
Some TTYs cannot recognize stutter dial tone (used by most voice mail services to indicate a waiting message) as a true dial tone. This interferes with the ability of the TTY to place a call whenever there are messages waiting.
Some TTYs have built-in printers (or the ability to connect to an external printer) and an answering machine function.
Some TTY users prefer to use their own voice during a call.
They speak during their turn, and read the other party’s typed replies
on the display. This is called voice carryover (VCO). There are VCO TTYs that have a display for the incoming typed
text and a handset for speech. There
are also VCO TTYs that also have a keyboard for full TTY functioning.
Some VCO TTYs have amplification.
Computers offer the potential for direct communication with TTYs. However, computer communication usually takes place in ASCII, which is not compatible with TTYs in their normal Baudot setting. This has been addressed for many computer platforms, either by installing a Baudot capable modem or by emulating the Baudot code set.
Most Baudot modems are actually dual-mode, since they can carry ASCII traffic as well, although usually at lower speeds than most commercially available ASCII-only modems. They are typically bundled with software that alerts the user to incoming calls and allows the user to open a TTY window on their screen for text conversations.
Since the Baudot protocol does not require a carrier or handshaking, there is little technical overhead to coding and decoding its signals in audio. Standard sound cards and telephone line interfaces or voice modems are used for this purpose. One software company plans to include this capability in the next release of its operating system, offering “virtual TTYs” to anyone with a compatible computer equipped with basic hardware.
Recently some manufacturers have begun offering a way to
turn every LAN workstation into a virtual TTY with only one TTY-capable modem.
See the PBX section for more details on LAN TTYs.
1193.41(c) Operable with little or no color perception.
1193.41(d) Operable without hearing.
1193.41(f) Operable with limited reach and strength.
1193.41(g) Operable without time-dependent controls.
1193.41(h) Operable without speech.
1193.43(c) Access to moving text.
1193.43(f) Prevention of visually-induced seizures.
1193.43(h) Non-interference with hearing technologies.
1193.51(c) Compatibility with prosthetics.
1193.51(e) TTY signal compatibility.
Communication aids are devices that allow a non-speaking person to communicate. Usually some combination of keys or switch connections are coded to refer to one or more words; various methods are embodied in a number of different designs. Some of these are standalone aids and some are computer programs. In most cases the final output is either digitized or synthesized speech.
Although no standalone communication aids have telephone features built into them, users often use them over the telephone. They are included in this Report because their use in conjunction with the telephone is a recurring issue for people with speech impairments.
The most common method is to use them next to a speakerphone. Two-thirds of the UCPA survey respondents find this “essential” (Simpson/UCPA, 1997). By placing the voice output communication aid close enough to the speakerphone’s microphone, the other party can hear the spoken output. Many users have difficulty lining up these two pieces of equipment.
Some communication aids are software-only, and run on a user-provided laptop or desktop computer. Some of these computers include telephone capability. Users can dial the number they want, and the speech synthesis output is played over the telephone line.
Some people with physical disabilities use environmental control units (ECUs) to operate lights and appliances through a customized switch or set of switches. For example, the user may be able to turn on and off a lamp, an overhead light, and a television by puffing and sipping through a tube in the proper sequence. These systems often have a telephone function built in, allowing the user to call a pre-programmed telephone number, or any telephone number by entering digits one at a time.