Terminal Equipment (TE) - Telephony for hearing impaired people - Characteristics of telephone sets that provide additional receiving amplification for the benefit of the hearing impaired; English version ETS 300488:1996
Edition 1996-08

Integrated Services Digital Network (ISDN); 3,1 kHz telephony teleservice; end-to-end compatibility requirements for telephony terminals; english version ETS 300082:1992
Edition 1992-06

Telephony for hearing impaired people - Inductive coupling of telephone earphones to hearing aids; English version ETS 300381:1994
Edition 1995-09

Dielectric and resistive properties of solid insulating materials - Part 2-1: Relative permittivity and dissipation factor - Technical frequencies (0,1 Hz to 10 MHz) - AC Methods (IEC 62631-2-1:2018); German version EN IEC 62631-2-1:2018
Edition 2018-12

Integrated Sevices Digital Network (ISDN); 3,1 kHz telephony teleservice; attachment requirements for handset terminals; english version ETS 300085:1990
Edition 1992-02