Voice over IP protocol families
There are currently four families of VoIP protocols: SIP, H.323 and H.248 based, and SIGTRAN.
Call Control
The call control protocols establish, modify and release connections.
SIP family
Based on IETF specifications:
SIP: "SessionInitiationProtocol" used for call control.
SDP: "SessionDescriptionProtocol" used to describe the "media" session inside of SIP and other protocols.
RTSP: "RealTimeStreamingProtocol" used to set up streaming sessions.
Sigcomp: "Signaling Compression " a solution for compressing messages generated by application protocols such as SIP and RTSP.
H.323 family
Based on ITU-T specifications:
H323: "Packet-based multimedia communications systems"
H225: "call control protocol"
H235: "Security"
H245: "Media control protocol"
H450: "Supplementary Services"
Q.931: "ISDN user-network interface layer 3 specification for basic call control"
H223: Multiplexing protocol for circuit-based multimedia communications system
To correctly dissect these protocols preference settings of TCP, TPKT, Q.931 and H225 must be correctly set.
H.248 family
Based on IETF specifications:
H248/MEGACO: "Media gateway Control Protocol" H248.1 RFC3015(Version 1)
SIGTRAN familiy
SIGTRAN is often used in connections towards PSTN.
Proprietary protocols
Cisco proprietary protocols:
SKINNY: Terminal control protocol.
Digium proprietary protocols:
Nortel proprietary protocols:
UNISTIM: A stimulus protocol for IP phones.
Transport
Both SIP and H323 uses the same RTP/RTCP transport protocols.
RTP: "RTP: A Transport Protocol for Real-Time Applications" RFC3550
T38: "Real-time facsimile (T.38), Fax-over-IP"
Movement toward secure communications involve these protocols
Authentication, Authorization and Accounting
Discussion
As far as I know MGCP is a VoIP family too. So you should put MGCP + H248 in call control section.- Cedric MILLET