The Swedish Institute of Assistive Technology (SIAT) has set the basic requirements of this document. It is used by local authorities and regions.
21 36 90 Total Conversation Units, Textphones and Videophones, 2005-09-01 (pdf, 160 kb, new window)
Presentation of Swedish Institute of Assistive Technology (pdf 1 MB, new window)
Short information about SIAT in several languages