The H series of ITU-T Recommendations addresses audiovisual and multimedia systems. See Table H-4 for selected H-series Recommendations.
| Recommendation | Description |
|---|
| H.100 | Visual telephone systems |
| H.222.1 | Multimedia multiplex and synchronization for audiovisual communication in ATM environments |
| H.223 | Multiplexing protocol for low bit rate multimedia communication |
| H.231 | Multipoint control units for audiovisual systems using digital channels up to 1920 kbit/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 1920 kbit/s |
| H.244 | Synchronized aggregation of multiple 64 or 56 kbit/s channels |
| H.245 | Control protocol for multimedia communication |
| H.248 | Gateway control protocol |
| H.261 | Video codec for audiovisual services at px64 kbit/s |
| H.263 | Video coding for low bit rate communication |
| H.310 | Broadband audiovisual communication systems and terminals |
| H.320 | Narrow-band visual telephone systems and terminal equipment |
| H.321 | Adaptation of H.320 visual telephone terminals to B-ISDN environments |
| H.322 | Visual telephone systems and terminal equipment for LANs that provide guaranteed QoS |
| H.323 | Packet-based multimedia communications systems |