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TTY Access to Voice Services

Background Paper


  AVSS Conference Logo: TTY keyboard with dialog balloon coming out of handset.

Jim Tobias

Inclusive Technologies

May 9, 2000


This paper provides some background to the participants of the Accessible Voice Systems and Services meeting, June 6-7, 2000, on the issues regarding TTY access to voice services.  Other disability implications will be covered separately at the meeting.



Although no clear statistics exist, it is likely that there are between 200,000 and 700,000 TTYs in use in the US.  The largest manufacturer, Ultratec, estimates the total at 300,000.  TTYs are sold largely through specialty distributors and are distributed free in about half the states of the U.S. through programs usually funded by surcharges to telephone bills.

  Image of a TTY.TTYs are small devices with single line LED or LCD displays and small, reduced-character-set keyboards.  They can be connected to telephone lines via acoustic couplers or RJ-11 jacks; some models have only one.  TTYs have some form of line status indicator, which allows users to see call status (ringing, busy, etc.) and the presence of a speech signal.

 Although modern TTYs can communicate in ASCII, almost all conversations occur in Baudot[1].  Baudot is an older telecommunications protocol, employing 5 bit FSK and a mode character to shift from letters to numbers.  The baud rate is 45.45, which allows for a typing speed of no greater than 60 words per minute.  Baudot does not use any error correction.  It is also half duplex: users alternate turns, with no simultaneous typing.  A conventional “GA” (for “Go ahead”) is typed to indicate that one’s message is complete[2].  Manufacturers have introduced proprietary protocols that allow for higher speeds and interruption.

 TTYs are used by four groups of people. The first is those whose severe hearing impairment began at birth or in early childhood, before they acquired language.  Many of these people consider themselves to be members of a Deaf culture, especially focusing on their use of American Sign Language (ASL).  Their TTY English may be colored by ASL’s word use and syntax.  The second group consists of those people whose hearing impairment is less severe, or who acquired their hearing impairment after they acquired language.  They may use a TTY in concert with speech where possible[3].  The third group includes those who are not hearing impaired, but who, due to another disability such as cerebral palsy, are not able to speak intelligibly over the telephone.  Some individuals in this latter group are also motor and mobility impaired.  The fourth group is those who use TTYs to communicate with members of the other three groups, and have no hearing or speech impairments themselves.

 In order to communicate with people who do not have TTYs, TTY users use the Telecommunications Relay Service (TRS).  See Appendix A for a brief description of TRS.

 Many TTY users are active users of telecommunications, and have commented on their interest in using voice mail systems (VMSs) and audiotext/IVR.  The following section describes some barriers to their ability to do so.



Record and Playback on Voice Mail

TTY users report that they can place and receive TTY messages on some private VMSs without difficulty, some with occasional loss of characters, and some not at all.  It is not confirmed whether public VM platforms share this variability, or whether they all can record and play back Baudot files accurately.  If the Baudot file is recorded accurately but a significant number of characters is lost in playback, the customer may be able to re-play the message in order to capture its meaning.  If the errors enter during recording, there is no solution.  This situation obtains for both outgoing and incoming messages.

Prompts and Navigation

A few TTY-users currently subscribe to voice mail systems without any TTY access features.  They can create outgoing Baudot messages and can retrieve incoming Baudot messages.  Their real reported problem is not with message storage and retrieval as much as with the user interface.  All system messages and prompts (how many new messages, message disposition, etc.) as well as the administrative interface (recording a new outgoing message, notification options, etc.) are all available only in spoken form.  For everyday use (not administrative setup) they have learned to pace the menus by both counting and watching their line status indicators.  They use a coupled telephone keypad for input at the appropriate moment.

This solution is not usable for audiotext/IVR systems, of course, unless the content is available in Baudot.

Many new voice platforms have a multi-language capability, designed to allow different sets of voice prompts for users with different language preferences.  This feature can be used to provide TTY prompts.  Baudot, like spoken languages, can be stored on audio files.  No carrier is present and there is no handshaking procedure.  The sole need appears to be Baudot files for all necessary system prompts and messages.

Some solutions may require a separate access number for TTY subscribers, much as some current multi-language services have separate access numbers for the different languages.  Other solutions may allow a single access number, with branching to the TTY version.  This branching may be based on identification of the calling line.  The separate access number or line identification solutions may not operate in the event of a network signaling failure.

Other branching options are a PIN entry (and customer database) or menu selection, requiring an integrated message as found in Appendix A.


TTY users may not have access to DTMF when they encounter an IVR.  Many calls are placed through TTYs that have modular plug connections (RJ-11).  This type of connection is commonplace because it supports an answering device in the TTY and avoids interference due to ambient noise.  Users can dial out from the TTY's keyboard; in some TTYs this is pulse dialing only.  DTMF has gradually become supported in TTYs, but on many models (and on TTY computer modems), DTMF either cannot be generated during a call, or requires a special sequence of keypresses to generate DTMF during a call.  (If the DTMF-generating phone is plugged in in parallel to the TTY, the DTMF signal is often too weak to control a voice system.)"

Baudot tone recognition poses some technical problems, as Baudot was not engineered for network recognition the way DTMF was.  In addition, DTMF recognition hardware is almost ubiquitous in the network.


Many TTY users live in households or work in offices with non-TTY users, with whom they share voice mail accounts.  This issue may complicate the interface requirements, as one cannot assume that a given call will be handled by voice or TTY.  This is one element of both the administrative and caller interfaces.  There are five sub-issues:

a. TTY-only accounts with single mailboxes have no additional problems with the interface.  They can use an integrated message (see Appendix A).  These accounts are most likely to operate TTYs without a voice telephone in parallel.

b. TTY-only accounts with multiple mailboxes need a method of prompting both their voice and TTY callers what to enter in order to put their message in the right mailbox.  Callers reach an account menu, and must enter a DTMF digit to enter an individual mailbox.  Currently this can be achieved through use of an integrated message (see Appendix A).  These accounts would have to create integrated messages for each mailbox, plus one for the account menu.

c. Mixed accounts with single mailboxes require a single integrated message (see Appendix A).

d. Mixed accounts with multiple mailboxes have the same problem as b.

e. Accounts with distinctive ringing have an additional problem regarding its interoperation with voice mail.  Not all switches forward the called number to the voice mail platform.  Therefore the VMS is only aware of the called line’s physical line number, and cannot provide a customized outgoing message.  Also, the forwarding feature cannot be turned on and off on a per-number basis.  This affects TTY users who may prefer to use their TTYs as answering machines: they must set their TTY ring count lower than the line’s ring count in order to do so.  There is currently no solution for this problem.


Currently some state TRS providers allow TTY users to access voice systems via a TRS call.  However, this is unsatisfactory to both the TTY user and the TRS provider.  The rate of speech is often faster than the Communication Assistant's (CA) typing speed.  TRS regulations require CAs to transcribe exactly what is spoken, in its entirety.  Thus messages may have be replayed to be fully transcribed, and the CA does not always know how to replay the message.  In fact, there is not always a way to have a message or prompt repeated. 

This problem often results in loss of messages or content, or multiple calls into the voice service.  Some users solve this by explaining the entire interface to the CA before the outgoing call is placed, including all menu navigation, PINS, etc.  TRS providers are not reimbursed for call set-up time, only for that portion of their time involved in direct transcription.

In addition, some users complain that TRS is not confidential enough for some of the IVR transactions they would like to perform.  They are concerned about revealing their PIN to the TRS CA.

See Appendix C regarding Comments to the FCC regarding access to voice services through TRS.

Appendix A

Telecommunications Relay Service



  TTY calling to TRS Center and CA talks to a hearing person on other side


[description of graphic – A line goes from a TTY on the left to a picture of a communication assistant in the center. On the right is a telephone with a line also going to the picture of the communication assistant]

TRS is an operator-assisted service between TTYs and voice telephones, mandated by the Americans with Disabilities Act.  In most (75% or more) TRS calls, a deaf or hard of hearing person (typically using a TTY) dials a toll-free number and requests that a call be made to a hearing person (voice party).  The TRS operator (called a “Communication Assistant” or “CA”) places the outbound call on a second line.  The conversation between the TTY user and the voice party takes place with the assistance of the CA, who speaks the typed messages for the benefit of the voice party, and types the spoken messages for the benefit of the TTY user.  

There are two variants from the standard TRS call.  In one, called Voice Carryover (VCO), the TTY user speaks during his/her turn, but reads the reply from the CA on the display.  This service is useful for those people who cannot hear phone conversation, but can speak and prefer to do so.  In the other, called Hearing Carryover (HCO), the TTY user types his or her message (which is read off by the CA), but hears the spoken reply.  This is useful for people who can hear and type but are speech impaired

Appendix B 

Integrated Messages


Integrated messages contain both Baudot (TTY text) and voice content in such a way that both voice- and TTY-users can be served from a single voice file.  They can be constructed as follows:

1. The Baudot letters “HD” or “HLD”, which are understood by TTY users to mean “Hold.”  This will secure the attention of any TTY users, while being short enough (less than 0.5 seconds) not to confuse or inconvenience hearing callers.

2. Any standard voice message, whether or not it requires a DTMF reply.  This message can indicate that TTY tones will follow, so the non-TTY caller should enter a menu selection or press a key to bypass the tones and proceed to leave a message.

3. A pause sufficient to convince hearing callers that there is no more information to be heard, approximately 5 seconds.  Presumably hearing callers will respond or hang up.

4. The appropriate transcription of the voice message in Baudot.

Integrated messages can be constructed by using both a TTY and a voice telephone on the same line, or by editing the two separate audio sources into one file.

NOTE: This may extend the duration of the message significantly.  Repeating or cycling of the message may be required in some contexts.

Appendix C

Legislative and Regulatory Background

1. Section 255 of the Telecommunications Act of 1996 in part states that:

`(b) MANUFACTURING: A manufacturer of telecommunications equipment and customer premises equipment shall ensure that the equipment is designed, developed, and fabricated to be accessible to and usable by individuals with disabilities, if readily achievable.

`(c) TELECOMMUNICATIONS SERVICES: A provider of telecommunications service shall ensure that the service is accessible to and usable by individuals with disabilities, if readily achievable.

`(d) COMPATIBILITY: Whenever the requirements of subsections (b) and (c) are not readily achievable, such a manufacturer or provider shall ensure that the equipment or service is compatible with existing peripheral devices or specialized customer premises equipment commonly used by individuals with disabilities to achieve access, if readily achievable.

The Federal Communications Commission has issued its regulations based on Guidelines developed by the Architectural and Transportation Barriers Compliance Board.  Voice mail and IVR systems are covered by this section under ancillary jurisdiction.  Below is the FCC’s language in the 96-198 Report and Order, with our added emphasis in points.

3.   Voicemail and Interactive Menus


93. The record has convinced us that in order for us to carry out meaningfully the accessibility requirements of  section 255, requirements comparable to those under section 255 should apply to two information services that are critical to making telecommunications accessible and usable by people with disabilities.  We assert ancillary jurisdiction to extend these accessibility requirements to the providers of voicemail and interactive menu service and to the manufacturers of the equipment that perform those functions.  By enacting section 255, Congress has charged the Commission with ensuring that telecommunications services and equipment are accessible to, and usable by, persons with disabilities. We cannot fully achieve that objective without this limited use of our ancillary jurisdiction.


97. Both voicemail and interactive menu services, and the related equipment that perform these functions, are at the very least "incidental" to the "receipt, forwarding and delivery of communications."  Indeed, the evidence here persuades us that  these two information services are not only incidental to communications, but essential to the ability of persons to effectively use telecommunications.  In reaching this conclusion, we are not breaking new ground, but are simply continuing our longstanding practice of asserting jurisdiction over voicemail and interactive menus.

 98. We note, however, that in the Computer II Reconsideration Decision we expressly reserved judgment on whether or not non-carrier-provided CPE would be subject to our Title I jurisdiction.  Similarly, we did not reach the question of whether the Commission had jurisdiction over information services provided by non-carriers.  We resolve these questions here in the affirmative.  These services and their related equipment are not less "incidental" to the "receipt, forwarding, and delivery of communications" because the services may be provided by non-carriers  in some instances.  Indeed, sections 1 through 3 of Title I of the Act are broadly worded and not limited in scope to communications by carriers.  Consistent with the statutory language, therefore, we find that our Title I subject matter jurisdiction over voicemail and interactive menu services, and related equipment, extends to that which is provided by carriers and non-carriers alike.  

99. The second step in our analysis requires us to evaluate whether, in this specific context, there is a statutory nexus supporting assertion of ancillary jurisdiction over voicemail and interactive menu service and manufacturers of equipment that performs those functions.  Framed somewhat differently, the test, as articulated by the Court of Appeals for the District of Columbia, is whether jurisdiction is "reasonably ancillary."  We find that the requisite statutory nexus exists, and employ ancillary jurisdiction to require that voicemail and interactive menu service and equipment must comply with requirements comparable to those under section 255.  We find, as described below, that these two discrete information services are both so integral to the use of telecommunications services today that, if inaccessible and unusable, the underlying telecommunications services that sections 255 and 251(a)(2) have sought to make available will not be accessible to persons with disabilities in a meaningful way. In short, inaccessible voicemail and interactive menus could defeat the effective implementation of sections 255 and 251(a)(2).

  100. Many commenters raised compelling examples of the importance of access to voicemail and interactive menus.  Both professional organizations and individual consumers reported how people with disabilities are hampered daily by lack of access to services others take for granted -- leaving a message for a colleague, reaching the desired person at a business, or simply receiving a phone call.  The Council of Organizational Representatives on National Issues Concerning People who are Deaf or Hard of Hearing (COR) concluded that  "without access to certain enhanced services, such as automated voice response systems and voice mail services, individuals who are deaf or hard of hearing will continue to be barred from enjoying even basic access to the telecommunications network."  Others explained that because of the prevalence of voicemail and interactive menus, unless these services are made accessible, the isolation of people with disabilities will be exacerbated, decreasing employment opportunities and reducing the participation of persons with disabilities in today's society.  UCPA summarized the concern with the observation that "voice mail, interactive telephone prompt systems, and Internet telephony are becoming available as mainstream services and are becoming critical to successful participation and competition in our society."

101. The access barriers created by inaccessible and/or unusable voicemail and interactive menus has made it extremely difficult for people with hearing, vision, or physical disabilities either to reach the party to whom they have placed the call or to obtain the information they seek in their phone call.  One commenter explains:

People with disabilities have been terribly affected by such lack of access; many menus offer no option to connect with a human operator and they remain cut off from communication.  They thus remain in the dark about how to fix their products and how to access other important information from private enterprises.

 102. Often all that is available at the other end of the line is an automated voicemail or menu system which is not accessible to or usable by people with disabilities.  For example, the voicemail or menu may not allow adequate time for a caller using the Telecommunications Relay Service to have the information from the automated device relayed to the caller's TTY and a response from the caller relayed back to the device through the Communications Assistant; or the sounds may be so quick that a person who is hard of hearing cannot process them quickly enough.   The speed of the menu choices can also create an access barrier for someone with a learning disability who cannot process the information fast enough.  The time allowed for a person to input the necessary numbers to retrieve voicemail messages, select an option from a list of choices or control the other functions may be too short for people with motor disabilities, or people who are blind.  In these instances, although the phone call may be completed in the technical sense of terminating the call, the call is not accessible to the person.  Despite the creation of a transmission path, if there is no means for a person to communicate with the mechanism at the other end, the telephone call is ineffective. 


 107. On this same basis, however, we decline to extend accessibility obligations to any other information services.  While some commenters have argued that there is an overwhelming need for all information services to be accessible to people with disabilities, we assess the record differently, and use our discretion to reach only those services we find essential to making telecommunications services accessible. Unlike voicemail and interactive menus, other information services discussed by commenters do not have the potential to render telecommunications services themselves inaccessible. Therefore, we decline to exercise our ancillary jurisdiction over those additional services.  Many of these other services are alternatives to telecommunications services, but not essential to their effective use. For example, e-mail,  electronic information services, and web pages are alternative ways to receive information which can also be received over the phone using telecommunications services. In contrast, inaccessible and unusable voicemail and interactive menus operate in a manner that can render the telecommunications service itself inaccessible and unusable.


2. TRS Rules (From 2/17/2000 Report and Order, CC Docket 98-67)


92. Interactive Menus and Voice Mail.  We are convinced by the record that today relay service does not provide consumers with a hearing or speech disability the ability to engage in communication by wire or radio in a manner that is functionally equivalent to those consumers without such a disability when the communication encounters an interactive menu.  We are concerned, as are many TRS users, that individuals with disabilities are being excluded from access to these ubiquitous technologies.  In order to provide TRS that is functionally equivalent to telecommunications service provided to voice users, we must interpret our duty under section 225 to include the authority to require access through TRS to interactive menus.  Interactive menu systems and recorded messages are increasingly used by businesses and services.  They present substantial barriers to TRS users because the speed at which information is provided is too fast to allow the TRS user to respond within the system response time.  As a result, TRS users are either unable to make calls that encounter interactive menus or other recorded messages or must frequently place a succession of calls to leave a message with, or access the information provided by, such systems.


93. The technologies to make these calls functionally equivalent are still being developed, and are required under Section 255 of the Act.  Section 255 requires telecommunication providers and manufacturers to make their services and products accessible to people with disabilities, if readily achievable.  Until we determine that such technology is fully deployed, we require that certain features be available to all relay users for the handling of these calls.


94. First, we will adopt our proposal, supported by commenters, to require CAs to alert the user to the presence of a recorded message through a “hot key” on the CA’s terminal.  The hot key would send text from the CA to the consumer’s TTY indicating that a recording or interactive menu has been encountered.   The consumer can respond by typing back instructions on how he or she wishes to proceed.  Commenters correctly point out that our current rules permit the consumer to ask the CA to summarize a message.  Because some relay facilities may be technically incapable of receiving “interrupt” messages, a caller using a TTY who does not request summarization before the CA begins typing a lengthy recorded message would have no choice but to receive the entire recorded message verbatim.  Our amendment gives these TTY users an opportunity to request summarization.  We encourage relay providers to consider whether a user’s preference to summarize messages should be included in the user’s customer profile.


95. Second, we adopt the suggestion of some commenters that we require relay centers to record these recorded messages, which could be retained for the length of the call. This will allow the CA to record the message at the relay center and rewind the message as needed to complete relaying of the message to the TRS user.  Because the CA would have a recording of the lengthy message, the CA would be able to finish relaying the message to the TRS user without having to redial the requested telephone number to hear the message time and again as she types it to the TRS user. 


96. Finally, oftentimes, consumers are unable to complete calls to interactive menus without repeating those calls.  We agree with consumers who argue that the statute prohibits consumers from being charged for repeated calls.  The statute and our current rules state that users of telecommunications relay services should pay rates no greater than the rates paid for functionally equivalent voice communication services.  Because voice callers can expect to complete their interaction with an interactive menu system in one call, relay users shall not be charged for additional calls needed to complete their interactions with recorded messages or interactive menu systems. We anticipate that TRS providers will include these added costs of completing these interactions in their overall costs of providing relay service, for reimbursement from the state and interstate TRS Funds.


97. A few commenters suggested requiring access to a live operator in lieu of a menu or recorded message.  Section 225, however, does not give us any express authority over the entities employing menus and recorded messages.  As noted above, however, we do expect that these features will become increasingly available as equipment manufacturers and service providers comply with our rules recently issued under section 255 of the Communications Act.


98. Pay-Per-Call Services.  Commenters have also asked us to require that pay-per-call services be offered through TRS.  The record clearly indicates that it is technically feasible for relay centers to accommodate calls to pay-per-call services. Pay-per-call services are services that are accessible through use of a 900 number.  The record shows that some relay providers already offer pay-per-call services, so we require relay service to offer pay-per-call as another component of functional equivalency.

 From the text of the Rule:

6. Voice mail and interactive menus. CAs must alert the TRS user to the presence of a recorded message and interactive menu through a hot key on the CA’s terminal.  The hot key will send text from the CA to the consumer’s TTY indicating that a recording or interactive menu has been encountered.  Relay providers shall electronically capture recorded messages and retain them for the length of the call.  Relay providers may not impose any charges for additional calls which must be made by the relay user in order to complete calls involving recorded or interactive messages.  Relay services shall be capable of handling pay-per-call calls.

 3. Section 508 Proposed Rule (Telecommunications Functions), from Access Board’s NPRM 3/31/2000, 36 CFR Part 1194, Docket No. 2000-01

  1)     TTY functionality

Telecommunication products that allow voice communication shall provide a standard non-acoustic connection point for TTYs; it shall be possible for user to turn a microphone on or off to allow the user to intermix speech with TTY use.

 2) TTY signals

Telecommunication products which include voice communication shall support the use of all cross-manufacturer non-proprietary standard signals.

  3) TTY compatibility with voice response systems

Voice mail, auto-attendant, and interactive voice response systems shall be usable with TTYs

 4) Adjustable response time interval

 Voice mail, messaging, auto-attendant, and interactive voice response systems shall provide at least one mode which does not require to respond within a time interval or allows adjustment to the timing and repetition of intervals to a minimum or 5 times the default

  5) Caller ID

Caller ID shall also be provide for users of TTYs, telecommunications relay services, and for users who cannot see display

  6) Volume control

For transmitted voice signal, telecommunication products shall provide a gain adjustable up to a minimum of 20 dB; and incremental volume control, at least one intermediate step increase of 12 dB.

  7) Default volume level reset

 If the telecommunications product allows a user to adjust output volume, a function shall be provided to automatically reset the volume to the default level after every use but not before.

  8) Audio transducer

Provide a means for effective magnetic wireless coupling to hearing technologies, if telecommunication product deliver output via audio transducer.

  9) Interference reduction

Interference to hearing technologies shall be reduced to the lowest possible level that allows utilization of the telecommunications product.

[1] Providers of relay service report that less than 5% of their traffic is carried in ASCII.

[2] Many other conventions and contractions govern TTY communication.

[3] TRS allows TTY users to speak during their turn, and receive the reply on the TTY.  This is called “voice carry-over”, or VCO


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