The Hi-Tech family of VoIP development solutions, which include SIP, H.323, MEGACO/H.248 and MGCP, offer the most comprehensive suite of real-time voice and video over IP communication protocols and testing tools used to develop standards-based voice and video over IP solutions. All of Hi-Tech's VoIP development solutions ensure the highest level of interoperability and deliver maximum flexibility for all necessary customization.
Here's a brief run down of the various protocols:
SIP
A signaling protocol for establishing real-time calls and conferences over IP networks
Client sends INVITE to SIP server asking party to join call
ACK may return other information (e.g., use compression)
Stateless; can be used for call signaling
Call Control Protocols H.323 and Related Protocols (ITU)
The most widely deployed IP communications protocol for real-time voice and video over IP
H.323, umbrella recommendation for packet communications of voice, fax, and video via Gateways between packet and legacy formats
H.225.0, control protocol, based on Q.931, for Gatekeeper that establishes calls
MGCP - Media Gateway Control Protocol (IETF)
A complementary protocol to H.323 and SIP, designed for controlling media gateways from external call control elements in decomposed gateway architectures
Used between a VoIP gateway and call agents
MEGACO/H.248
Similar to MGCP, the newest industry protocol for decomposed multimedia gateways
