Table VI. Video Teleconferencing Standards

	Narrow-band VTC (H.320)	Low Bitrate VTC (H.324)	Iso-Ethernet VTC (H.322)	Ethernet VTC (H.323)	ATM VTC (H.321)	High Res ATM VTC (H.310)
Video	H.261	H.261 H.263	H.261	H.261 H.263	H.261	MPEG-2 H.261
Audio	G.711 G.722 G.728	G.723	G.711 G.722 G.723 G.728	G.711 G.722 G.723 G.728 G.729	G.711 G.722 G.728	MPEG-1 MPEG-2 G.7xx
Data	T.120	T.120 T.434 T.84 Others	T.120	T.120	T.120 H.281 (H.224)	T.120
Multiplex	H.221	H.223	H.221	H.22z	H.221	H.222.1 H.221
Signalling	H.230 H.242	H.245	H.230 H.242	H.230 H.245	H.230 H.242	H.245
Multipoint	H.243	N/A	H.243	N/A	H.243	N/A
Encryption	(In draft revision) H.233 H.234	H.233 (adapted in H.324) H.234	(By reference to H.320)	TBD	H.233 H.234	N/A

ITU - T Multimedia conferencing standards

G.711:
     Audio encoding at 64 kb/s (mu-law and A-law). 

G.722:
     7 kHz Audio-coding Within 64 kbit/s 

G.723:
     Dual Rate Speech Coder for Multimedia Telecommunications Transmitting 
     at 6.4 and 5.3 kbit/s 

G.728:
     Coding of Speech at 16 kbit/s Using Low-delay Code Excited Linear 
     Prediction 

G.729:
     Coding of speech at 8 kbit/s using conjugate-structure 
     algebraic-code-excited linear-prediction (CS-ACELP) (9) 

H.221:
     Frame structure for a 64 to 1920 kbit/s channel in audiovisual 
     teleservices.

H.222.1:
     Multiplexing and synchronization of multimedia information for 
     audiovisual communications in ATM environment.

H.223:
     Multiplexing Protocols for Low Bitrate Multimedia Terminals

H.230:
     Frame-synchronous Control and Indication Signals for Audiovisual 
     Systems 

H.231:
     Multipoint Control Unit for Audiovisual Systems Using Digital Channels 
     up to 2 Mbit/s 

H.242:
     System for Establishing Communication Between Audiovisual Terminals 
     Using Digital Channels up to 2 Mbit/s 

H.243:
     Procedures for establishing communication between three or more 
     audiovisual terminals using digital channels up to 2 Mbit/s.

H.245:
     Control of Communications Between Multimedia Terminals 

H.261:
     Video encoding. 

H.263:
     Video encoding, improved version of H.261. 

H.320:
     Framework for transmitting audio and video over circuit-switched digital 
     networks (primarily ISDN).

H.321:
     Visual Telephone Terminals over ATM.
     (H.320 over ATM LAN.)

H.322:
     Visual Telephone Terminals over Guaranteed Quality of Service LANs.
     (H.320 over IsoEthernet LAN.)

H.323:
     Visual Telephone Terminals over Non-Guaranteed Quality of Service LANs.
     (H.320 over Ethernet, Token ring, etc. LAN.)

H.324:
     Audio and video over POTS at less than 20 kb/s.

T.120:
     Introduction to the audiographics and audiovisual conferencing 
     recommendations. 

T.121:
     Generic application template. 

T.122:
     Multipoint communication service for audiographics and audiovisual 
     conferencing service definition 

T.123:
     Protocol stack for audiographics and audiovisual teleconference 
     applications. 

T.124:
     Generic conference control. 

T.125:
     Multipoint communication service protocol specification. 

T.126:
     Still image protocol specification. 

T.127:
     Multipoint binary file transfer protocol. 

T.128:
     Audio Visual Control for Multipoint Multimedia Systems