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The conventional fixed-line telephone (ie plain old telephone system) has provided enormous benefits for many people with disabilities and older people. However the evolution from being solely an audio system to one which also carries data has introduced new possibilities as well as new problems.

Additional services, such as caller line identification and email, may require the use of a screen to display text and possibly graphics. These screen phones pose obvious problems for people with a visual or cognitive impairment, but there are methods for alleviating these problems.

Video phones have been slow to make significant market penetration. This is attributable to the low bandwidth available to most domestic consumers. For deaf users, a video phone could transmit sign language with a modest picture quality, but greater bandwidth is needed for lip reading.

Mobile communications are spreading, not only in quantity but also in diversity. More and more applications that either extend the traditional pattern of fixed communications or are entirely novel are appearing on the mobile market, with increasingly shorter times between launching events. This speed of development poses new problems on how to incorporate inclusive design in the development process.

The significant difference offered by the new systems is one of speed (see Table 1). For voice communication this difference is not significant, but for transferring large quantities of data, such as in video telephony or access to the web, the telecommunication companies are convinced that it is commercially viable.

Table 1 Maximum data speed of mobile systems



Maximum speed kbps
















The analogue systems are being largely superseded by digital systems except in remote areas where there are large distances between base stations.

The GSM (Global System for Mobile communications) digital system overcame many of the problems of poor signal reception in the analogue systems and increased available network capacity, but caused significant problems for many users of hearing aids.

With GSM systems the short message service (SMS) has proved very popular particularly among teenagers since it is inexpensive. The user interface is usually just the basic numeric keypad on the mobile phone, which requires multiple key presses with time sensitive input. This causes a significant problem for anyone with poor manual dexterity or a hand tremor.

WAP (Wireless Application Protocol) provides slow access to special websites. The service has not proved popular because of the slowness, the limitations of the small display on the mobile phone handset and the very limited number of services available. However the more advanced I-Mode system in Japan has proved a commercial success.

Extra functionality could be built into a WAP phone to suit disabled individuals, but this in itself is unlikely to provide full access to services. Therefore it will be necessary to modify the server or proxy server. The WAP User Agent Profile Specification covers aspects of the technical interface and the User Preference Profile concerns content selection (eg the user is interested in receiving sports scores); neither of these profiles covers the needs of people with disabilities.

This could be done in the form of a user profile, which is stored on the smart card in the user's phone. There is a European standard (EN 1332-4), but this will need to be extended to allow for the facilities needed by mobile phone users who have disabilities. This standard already incorporates facilities for specifying preferred text size, screen colour and speech output of the contents of the visual display.

GPRS (General Packet Radio Service) is a high-speed packet data technology, which, together with WAP, offers a means of upgrading GSM services towards the third generation systems. Use of GPRS will permit data transmission speeds over GSM networks of up to 100 kbps. Unlike GSM, GPRS systems are always connected so there is no delay caused by having to log on to the system.

UMTS (Universal Mobile Telecommunications System) is the third generation, after GSM and the analogue first generation, of mobile telecommunications systems. It should have seamless operation between terrestrial and satellite links, and will provide high-speed access to the Internet with data rates of up to 2 Mbps for a stationary terminal, less when on the move. It will include packet data transmission with the potential to adjust bandwidth on demand for asymmetric traffic. In the UK and Germany the network licences have been sold by governments for vast sums (the first five UK licences sold for over £22 billion), which will have to be recouped from the consumers. This, in addition to the start-up costs for a new infrastructure, will make the licence holders anxious to recover their outlay as quickly as possible by concentrating upon the most profitable sectors. They may be very reluctant to extend the service beyond these sectors and to provide tariff packages that would be attractive to disabled people and other disadvantaged consumers.

The high bandwidth and the text facility available with UMTS mean that text messaging could be as cheap and straightforward as voice calling, because the bandwidth would be paid for 'on demand' and not during waiting periods. It seems highly probable that this technology will transform the way that deaf people use text telephony.

Special services, which UMTS might offer, include:

  • Remote location and guidance (giving enquirers personal information on how to reach their destinations, with the service centre pin-pointing their locations automatically)
  • Remote interpretation for deaf people, by Sign Language or Lip-speaking (as soon as visual displays of adequate size and definition are available)

Realisation of these possibilities depends upon the third generation services developing quickly to the point where they reach, and are used by, the great majority of the general public.

Bluetooth is one example of a short-range wireless technology that can link appliances and devices together, so that control and communication can be managed remotely. It offers a number of very interesting and important applications for people with disabilities. Small devices that have tiny knobs - mobile phones, hearing aids, pocket calculators etc. - could be controlled from a separate keypad, appropriate to the user's needs, connected via a Bluetooth link. This is of great significance because the mobile phone itself could replace the remote control for televisions and video recorders. It can provide an interactive channel (for services such as tele-shopping) while connecting to the television via Bluetooth.

There has been much discussion about developing special mobiles with better accessibility, but all efforts to develop dedicated mobile phones for disabled people have been rejected, by disabled people themselves because they do not wish to be stigmatised as 'abnormal', and by the manufacturers because they regard this market as too small to be viable. The mobile phone business is characterised by high sales volumes and low prices with short product life spans. Dedicated products aimed at specific parts of the community tend to be made in low volumes, at high prices, and with long periods between design updates. This does not make them attractive for manufacturer or consumer.

Relevant standards

  • ACIF G586:2001 Access to telecommunications for people with disabilities.
  • 3GPP TS 22.101, Service principles, Brief description of mobile text conversation.
  • 3GPP TS 22.226, GTT Service Stage 1, GTT Specific service description.
  • 3GPP TS 23.226, GTT Architecture Stage 2, GTT Specific description of network architecture for text conversation and especially CTM text telephony.
  • 3GPP TS 26.110, Circuit Switched Multimedia Telephony. ( 3G.324 ), Includes text conversation using T.140 in AL1 channel.
  • 3GPP TS 26.226, CTM Modem, General description, Robust and error tolerant modem for text telephony specified for mobile networks.
  • 3GPP TS 26.235, Packet Switched Conversational Multimedia ( SIP ), Includes text conversation using T.140 in RTP as RFC 2793.
  • ACIF G586: (2001) Access to Telecommunications for People with Disabilities.
  • Alternative Interface Access Protocol.
  • ANSI/TIA-968-A, Telecommunications - Telephone Terminal Equipment - Technical Requirements for Connection of Terminal Equipment to the Telephone Network.
  • AS/ACIF S040: (1999) Requirements for general use Customer Equipment for use with the Standard Telephone Service - Features for special needs of persons with disabilities.
  • C.63/ANSI ANSI C.63.19, American National Standard for Methods of Measurement of Compatibility between Wireless Communication Devices and Hearing Aids, Measurements of wireless telephone emissions and hearing aid immunity, with predicted performance based on measures. (Now in use in an FCC order).
  • DEG HF 00031 Human factors guidelines for ICT products and services: Design for all.
  • DTR/HF 02003 (1996) The implication of human ageing for the design of telephone terminals.
  • DTR/HF 02009 (1996) Characteristics of telephone keypads.
  • EG 201 024 (1997) Human Factors (HF); User interface design principles for the Telecommunications Management Network (TMN) applicable to the "G" Interface.
  • EG 201 103 (1998) Human Factors (HF); Human factors issues in Multimedia Information Retrieval Services (MIRS).
  • EG 201 472 (2000) Human Factors (HF); Usability evaluation for the design of telecommunication systems, services and terminals.
  • EG 201 795 (2000) Human Factors (HF); Issues concerning User identification in future telecommunications systems.
  • EG 202 116 (2002) Human Factors (HF); Guidelines for ICT products and services: Design for all
  • EN 301 462 (March 2000) Symbols to identify telecommunications facilities for deaf and hard of hearing people.
  • EN 726 Requirements for IC cards and terminals for telecommunications use.
  • ES 201 125 (1998) Human Factors (HF); Universal Personal Telecommunications (UPT); Specification of the minimum Man-Machine Interface (MMI) for Phase 1 UPT.
  • ES 201 275 (1998) Human Factors (HF); User control procedures in basic call, point-to-point connections, for Integrated Services Digital Network (ISDN) videotelephony.
  • ES 201 381 (December 1998) Telecommunication keypads and keyboards: Tactile identifiers.
  • ETR 160 (1995) Human factors aspects of multimedia telecommunications.
  • ETR 165 (1995) Recommendations for a tactile identifier on machine readable cards for telecommunications terminals.
  • ETR 167 (1995) User instruction for public telecommunication services: design guidelines.
  • ETR 170 (1995) Human Factors (HF); Generic User control procedures for telecommunication terminals and services.
  • ETR 208 (1995) Human Factors (HF): HF Aspects of universal personal telecommunications (UPT); User requirements.
  • ETR 261-1 (1996) Human Factors (HF); Assessment and definition of a harmonized minimum man-machine interface (MMI) for accessing and controlling public network based supplementary services; Part 1: General approach and summary of findings.
  • ETR 333 (1998) Text Telephony: Basic User Requirements and Recommendations.
  • ETR 334 (1996) The implications of ageing for the design of telephone terminals.
  • ETR 345 (Jan 1997) Characteristics of telephone keypads and keyboards; Requirements of elderly and disabled people.
  • ETS 138 (1998) Public terminals for the elderly.
  • ETS 300 375 (November 1994) Pictograms for point to point videotelephony.
  • ETS 300 381 Telephony for hearing impaired people: Inductive coupling of telephone earphones to hearing aids.
  • ETS 300 488 (January 1996) Telephony for hearing impaired people: Characteristics of telephone sets that provide additional receiving amplification for the benefit of the hearing impaired.
  • ETS 300 679 (September 1996) Telephony for the hearing impaired: Electrical coupling of telephone sets to hearing aids.
  • ETS 300 738 (1997) Human Factors (HF): Minimum Man Machine Interface (MMI) to public network based supplementary services.
  • ETS 300 767 (July 1997) Telephone prepayment cards: Tactile identifier.
  • H Series Supplement 1, Video Quality for sign language and lip reading, Quality characteristics of video transmission of importance for sign language and lip-reading use.
  • HFES 200.3:, Human Factors Engineering of Software User Interfaces, Software interface standard (Standard now includes 5 interface strategies developed by Trace).
  • HFES 200.5:, Human Factors Engineering of Software User Interfaces - Interactive Voice Response (IVR) and Telephony, A user interface standard for IVRs and voice mail.
  • IETF draft RFC Framework of requirements for real-time text conversation using SIP.
  • IETF RFC 2733 An RTP Payload Format for Generic Forward Error Correction. Error correction method.
  • IETF RFC 2793 RTP Payload for Text Conversation. RTP Payload for T.140 text conversation. MIME Registered as "text/t140", used in H.323 and SIP.
  • IETF RFC 2833 RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals. Encoding and transport of tones over IP.
  • IETF RFC 3351 User requirements. Handles transcoding and other value added services invoked through SIP.
  • ISOC/IETF RFC 3261 (2002) IETF RFC 2543 SIP Session initiation Protocol. Session initiation Protocol - used to connect Voice over IP (Internet Protocol) phone calls.
  • ITU Y.1541, Network performance objectives for IP-based services.
  • ITU-T E.118 (2001) Automatic international telephone credit cards.
  • ITU-T E.121 (1996) Pictograms, symbols and icons to assist Users of the telephone service.
  • ITU-T E.133 (1988) Operating procedures for cardphones.
  • ITU-T E.134 (1993) Human factors aspects of public terminals: Generic operating procedures.
  • ITU-T E.135 (1993) Human factors aspects of public telecommunications terminals for people with disabilities.
  • ITU-T E.136 (1997) Tactile identifier on pre-paid telephone cards.
  • ITU-T E.161 (1995) Arrangements of figures, letters and symbols on telephones.
  • ITU-T E.902 (1995) Interactive services design guidelines.
  • ITU-T E.920 (1995) Procedures for designing, evaluating and selecting symbols, pictograms and icons.
  • ITU-T P.370 (1996) Magnetic field strength around the earcap of telephone handsets which provide for coupling to hearing aids.
  • ITU-T Rec. F.700, Famework Recommendation for multimedia services, Annex A.3., Multimedia Framework.
  • ITU-T Rec. F.703, Multimedia conversational services, Defines Text Telephony and Total Conversation services.
  • ITU-T Rec. H.245, Control Protocol for Multimedia Communication, Multimedia Control protocol.
  • ITU-T Rec. H.323 Annex G;(02/00), Text Conversation and Text SET., Defines T.140 text inclusion in H.323 IP Multimedia.
  • ITU-T Rec.H.320, Narrow-band visual telephone systems and terminal equipment.
  • ITU-T Rec.H.324, Terminal for low bit-rate multimedia communication, Addition of data channel for T.140 text.
  • ITU-T Rec.T.134, Text Chat Application Entity, Application for text conversation in the T.120 data conferencing concept.
  • ITU-T Rec.T.140 - Addendum, Marking of missing characters, Marking of missing characters.
  • ITU-T Rec.V.151 (under development), Procedures for the end-to-end connection of analogue text telephones over an IP network.
  • ITU-T Rec.V.152 (under development), Procedures for supporting Voice Band Data over IP networks.
  • ITU-T Rec.V.250, Serial asynchronous automatic dialling and control.
  • ITU-T Recommendation H.224, A real time control protocol for simplex applications using the H.221 LSD/HSD/HLP channel., Addition of client id=2 for T.140 text transport.
  • ITU-T Recommendation H.248, Gateway control protocol, Text conversation protocol for multimedia application. With amendment 1 (2000). Control of gateway between all forms of text conversation.
  • ITU-T Recommendation T.140, Protocol for multimedia application text conversation., Text conversation protocol for multimedia application. With amendment 1 (2000).
  • ITU-T Recommendation V.18, Operational and Interworking Requirements for DCE:s Operating in the Text Telephone Mode, Includes automatic interworking with most legacy text telephones.
  • ITU-T Recommendation V.61, Analog simultaneous voice and data (permits Voice carry over with ASCII modems.
  • ITU-T Recommendation V.8 bis, Procedures for the identification and selection of common modes of operation between Data Circuit-terminating Equipments (DCEs) and between Data Terminal Equipments (DTEs) over the public switched telephone network, Operational and interworking requirements for DCE:s operating in the text telephone mode.
  • ITU-T Recommendation V.8, Procedures for starting sessions of data transmission over the public switched telephone network.
  • ITU-T Study Group 16 v.150.1, Modem over IP, International Recommendation for transport of Modem over IP.
  • ITU-T Study Group 16 V.ToIP (in process) QH-03001, Text Telephony over IP, International standardization to develop a new Recommendation for Text Telephony over IP.
  • ITU-T Study Group 16 V.VBS (in process), Voice Band Data over IP, International standardization to develop a new Recommendation for Voice Band Data over IP. Useful for text telephony over enterprise networks.
  • T1 T1.209-2003, American National Standard for Operations Administration and Maintenance and Provisioning (OAM&P) - Network Tones and Announcements, Provides and industry standard way for network routing messages to be conveyed in TTY in addition to voice.
  • T1. 719-2001, PCS 1900 - Cellular Text Telephone Modem (CTM) General Description.
  • T1.718-2001, PCS 1900 - Cellular Text Telephone Modem (CTM) Transmitter Bit Exact C-Code.
  • TC TR 001 (1991) Human Factors (HF): Generic Handsfree Procedures.
  • TC TR 003 (1992) Human Factors (HF): Human Factors Aspects of Pan European Numbering.
  • TC TR 004 (1992) Human Factors (HF); Harmonisation of code schemes as minimum Man Machine Interface for Telecommunication Terminals.
  • TC TR 006 (1995) Human Factors (HF): Satellite Personal Communication Network; statement of User aspects for a S-PCN service.
  • TC TR 007 (1996) Human Factors (HF); User requirements of enhanced terminals for public use.
  • TCR-TR 023 (1994) Assignment of alphabetic letters to digits on push button dialling keypads.
  • TIA- 504-A, Telecommunications-Telephone Terminal Equipment-Magnetic Field and Acoustic Gain Requirements for Headset Telephones Intended for Use by the Hard of Hearing.
  • TIA IS-127-2, Enhanced Variable Rate Codec, Speech Service Option 3 for Wideband Spread Spectrum Digital Systems - Addendum 2.
  • TIA IS-707-A-2, Data Services Options for Spread Spectrum Systems - Radio Link Protocol Type 3 - Addendum No. 2.
  • TIA IS-733-1, High Rate Speech Service Option 17 for Wideband Spread Spectrum Communications Systems.
  • TIA IS-789A, Electrical Specification for the Portable Phone to Vehicle Interface.
  • TIA IS-823, TTY/TDD Extension to TIA/EIA 136-410 Enhanced Full Rate Speech Codec.
  • TIA -IS-840, Minimum Performance Standards for Text Telephone Signal Detector and Text Telephone Signal Regenerator.
  • TIA TSB-121, 2.5 mm Audio Interface For Mobile Wireless Handsets - Text Telephones (TTY).
  • TIA/EIA-688, DTE/DCE Interface For Digital Cellular Equipment.
  • TR 101 806 (June 2000) Guidelines for telecommunications relay services for text telephones.
  • TR 102 068 (2002) Requirements for Assistive Technology Devices in ICT.
  • TR 30 TIA/EIA 825a, A Frequency Shift Keyed Modem for use on the Public Switched Telephone Network, The first standard for TTY signals, which permitted mainstream industry to design for compatibility with TTY as technologies moved to digital.
  • TR 30.1 TIA 1001 (in process), Standards for text over IP (TIA 1001), U.S. effort to develop standard methods for carrying Baudot over IP telephony networks, using voice band data and gateway approaches.
  • TR 45 TSB-121, 2.5 mm Audio Interface For Mobile Wireless Handsets - Text Telephones (TTY), Connector standard for wireless telephones and TTYs.

Further information

  • The Forgotten Millions: Access to Telecommunications for People with Disabilities
  • Telecommunications: The Missing Links for People with Disabilities
  • Issues in Telecommunications for People with Disabilities
  • Telecommunications for All
  • Telecommunications: Guidelines for Accessibility.
  • US Telecommunications Act Accessibility Guidelines
  • Self-evaluation form
  • Section 508 guidelines on telecommunication products
  • Include This is the main European website concerned with designing information and communication technology systems so that they are accessible to everybody including disabled and elderly people. This site contains a wealth of information including demographics of disability in Europe, relevant standards as well as legislative aspects.
  • COST 219bis This group of 21 countries is concerned with access to telecommunications by disabled and elderly people. Their site contains much detailed information about access to telecommunication systems and services by disabled and elderly people.
  • Trace Center This is the main American website concerning access to new technology by people with disabilities.
  • Center for Universal Design
  • Irish Accessibility Guidelines for Telecoms
  • Human Factors Guidelines for Designers of Telecommunications Services for Non-expert Users. HUSAT, Loughborough University, 1996.
  • Brandt A (ed) Telephones for All. Nordic Committee on Disability, 1994
  • Bridging the Gap? Access to Telecommunications for All People


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