Built-in shelves or counters for public telephones must be designed to accommodate persons using text telephones (TT).
These devices may also be referred to as teletypewriters (TT) or telecommunication devices for the deaf (TDD). These devices require a level surface at least 500 mm wide by 350 mm deep with no obstruction above that space within 250 mm.
If a wall-hung telephone or other obstruction extends to less than 250 mm from the shelf or counter, an equivalent clear space must be provided on either side of each telephone.
At least one telephone should be equipped with a volume control on a receiver that generates a magnetic field compatible with the T-switch of a hearing aid. The lower portion of the shelf or counter is intended for persons using a wheelchair; therefore, all parts of the operating mechanism of the telephone above this portion should be within the reach of a wheelchair user.
