This document is to be a general overview of the implementation of multimedia terminals targeting audiovisual conferencing applications on the GSTN. This document also provides elaboration of implementation details in areas which the ITU-T documents have been found to be vague or unclear. Detailed standards for implementation of compatible terminals are provided by normative reference to approved ITU-T Recommendations. Multimedia terminals according to this standard which comprise combined video and audio (Videophones) shall include means for conventional telephony interworking with telephone terminals on the GSTN. Means for interworking with other modem or FAX terminals which may utilize the GSTN are optional. Such additional arrangements are outside the scope of this standard. Wireless operation is beyond the scope of this standard. Purpose The purpose of the document is to provide the reader a general understanding of the implementation of multimedia terminals targeting audiovisual conferencing applications on the GSTN. Its technical content is purposely left as an overview and technical implementation details are to be found in the referenced ITU-T recommendations. A detailed normative reference list of all applicable ITU-T and ISO/IEC recommendations is included.