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Plain Old Telephone System

Many disabled people would be helped by some extra appropriate features on their telephone. Which feature or combination of features is needed will vary from individual to individual. Possible features include:

  • Coupling to a hearing by inductive coupling, infra-red, direct electrical connection or by matched acoustic transducers.
  • Hearing aid compatibility so that there is no mutual interference, and with minimal change to the setting of the hearing aid.
  • Receiver amplification enables the user to increase the volume of sound (up to 20 dB) coming through the telephone earpiece.
  • Additional earphone enables a user to listen with both ears. Can also be used by a hearing helper who can repeat the message so that it can be lip read.
  • Microphone amplification will help persons with quiet voices or with restricted neck and chest movement that makes speaking difficult.
  • Sidetone reduction is a facility for improving the signal to noise ratio at the earphone by minimising the effects of ambient noise picked up by the microphone and mixed with the incoming speech.
  • Ringer pitch adjustable is useful whose hearing loss is significantly frequency dependent.
  • Ringer volume adjustable gives the possibility to provide good audibility even in domestic environments where acoustic absorption may be high.
  • Visual ringing signal is essential for people who are deaf. Visual signals incorporated in the terminal are not easily seen and are mainly of use as a reminder of line status. An interface should be provided so that external lights or a vibrating pager can be triggered by the phone.
  • Enlarged keys enable persons with poor dexterity to pres the correct key; the spacing between the keys is as important as the size of the keys themselves. A concave shape to the keys will also help fingers to stay in place.
  • Guarded or recessed keys can help a person who has difficulty in making precise finger movements.
  • A dial-out buffer memory enables users who are slow in dialling to avoid being timed-out.
  • Tactile key markers help people who are blind or have low vision.
  • The keys should be marked with a large clear typeface.
  • Standard key layouts are important for people who are blind or who have difficulty in reading the key legends.
  • A plug-in keyboard enables the user to use a device which is customised to their particular needs.
  • A large character display is essential for many people with a visual impairment.
  • The visual display should be high contrast.
  • A tactile display may be useful for services such as caller line identification for blind people who can read Braille.
  • A synthetic speech alternative to the visual display would help many blind people. A means of adjusting the volume and of repeating the messages will be required.
  • A means of adjusting the key pressure to activate a key is desirable.
  • Tactile feedback that confirms that a key has been pressed can be very helpful.
  • Audible confirmation of a key press is helpful for many visually impaired people.
  • Users with impaired hearing may require a displayed indication of the number dialled.
  • A keypad in the handset can cause problems for persons with poor manual dexterity or reduced strength.
  • Hands-free operation is valuable for users with sever upper limb impairments, but it must include the call set-up procedures.
  • Speech-input keying is useful for those with hand tremors or a cognitive impairment.
  • A text send keyboard is required by deaf users who may be using a relay service.
  • A non-slip base on a phone not designed for fixed mounting is highly desirable for people with uncoordinated movements.
  • The handset should be easy to grip with sufficient space between the handset and the telephone base unit so that the handset can be picked up and replaced with ease.

Checklist for Plain Old Telephone System

Relevant standards

  • ACIF G586:2001 Access to telecommunications for people with disabilities.
  • ETR 029 Access to telecommunications for people with special needs: Recommendations for improving and adapting telecommunication terminals and services for people with impairments.
  • DTR/HF 02009 (1996) Characteristics of telephone keypads.
  • ETS 300 381 Telephony for hearing impaired people: Inductive coupling of telephone earphones to hearing aids.
  • ETR 167 (1995) User instruction for public telecommunication services: design guidelines.
  • TCR-TR 023 (1994) Assignment of alphabetic letters to digits on push button dialling keypads.
  • DTR/HF 02003 (1996) The implication of human ageing for the design of telephone terminals.
  • ETS 300 388 (December 1994) 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.
  • EN 301 462 (March 2000) Symbols to identify telecommunications facilities for deaf and hard of hearing people.
  • ES 201 381 (December 1998) Telecommunication keypads and keyboards: Tactile identifiers.
  • TR 101 806 (June 2000) Guidelines for telecommunications relay services for text telephones.
  • IEC 118-4 Hearing aids: magnetic field strength in audio frequency induction loops for hearing aid purposes.
  • ITU E133 Operating procedures for cardphones.
  • E134 Human factors aspects of public terminals: Generic operating procedures.
  • E135 Human factors aspects of public telecommunications terminals for people with disabilities.
  • E161 Arrangements of figures, letters and symbols on telephones.
  • P370 Magnetic field strength around the earcap of telephone handsets which provide for coupling to hearing aids.

Further information


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