H323 is a set of standards from ITU-T that provides a set of protocols for offering audio and video communication over a computer network.

H323 is a relatively old protocol and is now replaced by the SIP Protocol – Session Initiation Protocol. One of the advantages of SIP is that it is a much less complex protocol and resembles protocols like HTTP / SMTP.

Therefore, most VOIP equipment available today follow the SIP standard. However, older equipment rather follow the VOIP H 323 standard.

What is SIP – Session Initiation Protocol

The SIP, short for Session Initiation Protocol, is an IP telephony signalling protocol used for initiating, managing and terminating phone calls using VOIP. SIP was created by IETF organization and published as IETF RFC 3261

SIP describes the communication needed to make a phone call. The details are further described in the SDP protocol.

SIP has made a big buzz in the world of VOIP. The protocol is similar to HTTP, its text-based and is very open and flexible. Therefore, it has largely replaced the standard H323.