This standard specifies the interface indicators for 64~1920 kbit/s conference television systems entering the digital network, the ability of conference television equipment to adapt to channel errors, the interconnection methods between conference television terminals, and the basic technical requirements for equipment entering the network. This standard is applicable to the opening of domestic and international point-to-point or multi-point conference television services. The formulation of this standard provides technical basis for the development of conference television systems, equipment selection, and equipment network access testing. 2. Reference standard GB 7611 Pulse Code Modulation Communication System Network Digital Interface Parameters ITU-TH.320 Narrowband Videophone System and Terminal Equipment ITU-TH.281 Video Codec for Video Services Using H.224 Conference Television Remote Camera Control Procedures ITU-T H.261 PX64 kbit/s Audiovisual Services ITU-T H.243 Method for Establishing Communication between 3 or More Audiovisual Terminals Using 2 Mbit/s Channels ITU-T H.242 Establishment of Audiovisual Terminals Using Until 2 Mbit/s Digital Channels Communication system between terminals ITU-TH.233- Encryption system for audiovisual services ITU-TH.231 is used as a multi-point controller for audiovisual systems up to 2 Mbit/s digital channels. ITU-TH.230 provides frame synchronization control and indication signals for audiovisual systems. ITU-TH.221 provides frame structure for 64 to 1920 kbit/s channels in audiovisual telecommunications services. ITU-T G.735 operates at 2048 kbit/s and provides synchronous 384 kbit/s digital access and/or synchronous 64 kbit/s digital access base group multiplexing equipment Characteristics of ITU-T G.728 Using Low Delay Codebook Excitation Linear Prediction Method for Speech Coding at 16 kbit/s ITU-T G.722 7 kHz Audio Coding in 64 kbit/s ITU-TG.711 Audio (Voice Frequency) Pulse Code Modulation (PCM)