This standard specifies the technical characteristics (electrical@ logical and acoustic) for terminal equipment for the 3.1 kHz telephony teleservice which can be connected to an ISDN basic access. The requirements of this standard are additional to those of the standards for connection to the ISDN basic access@ and of any other standards to which the terminal equipment is subject. This standard is applicable to simple telephony terminals as well as to the telephony function of multifunction or multi-service terminals. This standard is applicable to terminal equipment of the functional group defined as Terminal Equipment Type l (TEl) in CCITT Recommendation I.411 [10] which supports the 3@1 kHz telephony teleservice. This standard applies to apparatus for household@ office and similar general indoor use.The terminal includes all the functions necessary to provide real-time 2-way speech conversation. Where a function is indicated as optional@ it need not be provided@ but where such a function is provided@ the terminal shall conform to the requirements and tests specified in this standard. This standard is not applicable to: a) terminal equipment specially designed for the disabled (e.g.@ with amplification of received speech as an aid for the hard-of-hearing); b) terminal equipment using a radio link (e.g.@ cordless telephones); c) terminal equipment for hostile environments. NOTE 1: This standard is applicable only to items of terminal equipment with an integral usernetwork interface for ISDN basic access. Where an adaptor is used@ other standards may apply. NOTE 2: In some countries@ an interim ISDN service corresponding to@ but not wholly compatible with@ the ISDN basic access standards may be provided. For connection to such services@ this standard is not applicable.