VoIP Standards
Signalling:
ITU-T Standards and Recommendations
| H.323 V2 | Packet-based mutlimedia communications systems |
| H.225.0 | Call signalling protocols and media stream packetization for packet-based multimedia (includes Q.931 and RAS) |
| H.225.0 Annex G | Gatekeeper to gatekeeper (inter-domain) communications |
| H.245 | Control protocol for multimedia communications |
| H.235 | Security and encryption for H-series multimedia terminals |
| H.450.x | Supplementary services for multimedia: 1. Generic functional protocol for the support of supplementary services in H.323 2. Call transfer 3. Diversion 4. Hold 5. Park & pickup 6. Call waiting 7. Message waiting indication |
| H.323 Annex D | Real-time fax using T.38 |
| H.323 Annex E | Call connection over UDP |
| H.323 Annex F | Single-use device |
| T.38 | Procedures for real-time group 3 facsimile communications over IP networks |
| T.120 series | Data protocols for multimendia conferencing |
IETF RFCs and Drafts
| RFC 2543 | SIP: Session initiation protocol |
| RFC 2327 | SDP: Session description protocol |
| Internet Draft | SAP: Session announcement protocol |
Gateway Control:
ITU
| H.GCP | Proposed recommendations for gateway control protocol |
IETF
| Internet Draft | MGCP: Media gateway control protocol |
| Internet Draft | MEGACO protocol |
| Draft | SGCP: Simple gateway control protocol |
| Internet Draft | IPDC: IP device control |
Media Transport:
IETF
| RFC 1889 | RTP: Real-time transport protocol |
| RFC 1889 | RTCP: Real-time transport control protocol |
| RFC 2326 | RTSP: Real-time streaming protocol |
Media Encoding:
ITU Voice
| Standard | Algorithm | Bit Rate (Kbit/s) | Typical end-to-end delay (ms) | Resultant Voice Quality |
| G.711 | PCM | 48, 56, 64 | <<1 | Excellent |
| G.723.1 | MPE/ACELP | 5.3, 6.3 | 67-97 | Good(6.3), Fair(5.3) |
| H.728 | LD-CELP | 16 | <<2 | Good |
| G.729 | CS-ACELP | 8 | 25-35 | Good |
| G.729 annex A | CS-ACELP | 8 | 25-35 | Good |
| G.722 | Sub-band ADPCM | 48, 56, 64 | <<2 | Good |
| G.726 | ADPCM | 16,24,32,40 | 60 | Good(40), Fair(24) |
| G.727 | AEDPCM | 16, 24, 32, 40 | 60 | Good(40), Fair (24) |
Video
| Standard | Algorithm | Bit Rate (Kbit/s) | Picture Quality |
| H.261 | Discrete cosine transform (DCT) with motion compensation | px64 (p=# of ISDN B channels) | Low |
| H.263 | Improved version of H.261 | Various | Medium |
| H.264 | Advanced Video Coding (AVC) | Various | High |