This second edition of Part 1 of this Interim European Telecommunication Standard (I-ETS) specifies the technical characteristics (electrical, logical and acoustic) for telephony terminals to be used at the basic access of the coincident S and T reference point of the Integrated Services Digital Network (ISDN). The characteristics of this I-ETS are additional to any other Standard or attachment requirements to which the Terminal Equipment (TE) is subject (note 1).