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Video Telephones

Terminals that can display sign language or permit lip-reading will be especially valuable for users with severe hearing difficulties. The definition and frame update rate on PSTN (Public Switch Telephone Network) connected videophones are not currently adequate for this usage. Sign language has its own grammar and syntax and is regarded as a language in its own right, so those who use it may regard written English (ie. text) as foreign. This group of users, which includes many of those who were born deaf, will not be well served by the telephone network until high definition video telephony is readily available.

Few countries, as yet, offer a video relay service which permits a sign language user to communicate with a hearing person or a text user with the help of a human operator. However, this type of service could come more significant with the introduction of third generation (UMTS) mobile phones which have a video capability.

Dedicated videophones and PC multi-media systems offer the possibility of communicating visually. This would allow objects to be shown visually, as well as allow signing to a deaf person. With more elderly people living alone, a simple to use video telephone can provide greater security and independence. Research in Sweden has shown that video phones can be very useful for someone with an intellectual impairment.


  • Good lighting and contrast between the person and a plain background can improve visual clutter; this is particularly important for reading sign language.
  • Typefaces should be clear with high contrast backgrounds.
  • The ability to select larger type or special volume settings will be helpful for persons with visual or hearing impairments.
  • A keyboard will permit the addition of text messages which can be particularly useful for deaf persons.
  • Visual and sound indication of line status will help persons with low vision or hearing impairments.
  • Visual indicator for ringer, or a socket for external flashing light, is particularly important for hearing impaired users.
  • Higher bandwidth and better processing will permit lip reading as well as sign language communication which requires at least 25 frames per second.

Relevant standards

  • ETSI ETR 160 (1995) Human factors aspects of multimedia telecommunications.
  • ETSI ETS 300 375 (November 1994) Pictograms for point to point videotelephony.

Further information


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