H.323, H.225.0, and H.245 Versions (Q105)

The information in this article applies to:

This article describes in tabular form what H.323 describes in prose, making it perhaps a bit easier to understand how the versions of the three main Recommendations relate to each other.

A product claiming compliance with H.323 shall be compliant with a particular version of H.323 and shall therefore comply with the H.323 Recommendation whose ratification date corresponds to the H.323 Version in Table 1. Each version of the H.323 Recommendation references the corresponding versions of the H.225.0 and H.245 Recommendations indicated in Table 1. There is no explicit H.323 version indicator in any message used by H.323. The version of H.323 is identified by H.225.0 messages containing protocolIdentifier = {itu-t (0) recommendation (0) h (8) 2250 version (0) x}, where "x" is indicated in Table 1 as the H.225.0 Version for the corresponding H.323 Version. A product shall encode H.245 messages containing protocolIdentifier = {itu-t (0) recommendation (0) h (8) 245 version (0) y}, where "y" is indicated in Table 1 as the H.245 Version for the corresponding H.323 Version.