Protocols
Most standards-based solutions use either the H.323 or Session Initiation Protocol (SIP) protocols. A number of proprietary designs also exist. These typically support features such as call waiting, conference calling, and call transfer.
Transport protocols:
- SRTP
- Existing secure transport protocol
- RTP
- Unsecure transport protocol
- ZRTP
- New secure transport protocol proposal
Signaling protocols:
- Session Initiation Protocol (SIP)
- defined by the IETF, newer than H.323
- H.323
- defined by the ITU-T
- Megaco (a.k.a. H.248) and MGCP
- both media gateway control protocols
- Skinny Client Control Protocol
- proprietary protocol from Cisco
- MiNET
- proprietary protocol from Mitel
- CorNet-IP
- proprietary protocol from Siemens
- IAX
- the Inter-Asterisk eXchange protocol used by the Asterisk open source PBX server, Yate and associated client software
- Skype
- a proprietary peer-to-peer protocol used in the Skype application
- Jajah
- a proprietary peer-to-peer protocol used in the Jajah SIP and IAX compatible webphone
- Jingle
- open peer-to-peer protocol based on XMPP (Jabber) and being harmonised with the 'substantially equivalent' Google Talk protocol.
Several different speech codecs can be used for stream audio compression. Commonly used codecs for VoIP traffic include G.711, G.723.1 and G.729, all ITU-T-specified.
More VoIP related topics:
- VoIP non-profit bodies and organization.
- VoIP ATAs, gateways and switches vendors.
- VoIP top service providers
- VoIP news and updates.
- VoIP resources and statistics.
- VoIP testing tools (hardware and software).
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- VoIP special products and services.
- VoIP learning curve.
- VoIP where to buy?
- VoIP related and interesting links.