H.323/SIP comparison

Although the ITU-T and IETF approaches share the same goal in terms of signaling telephone calls and multimedia in general, they differ considerably in the philosophy they adopt.

The ITU-T's approach, although based on the standards it had previously defined for the Integrated Services Digital Network (ISDN), defines a set of new protocols dedicated to Internet telephony (in the broadest sense), as well as the equipment that implements these protocols. In contrast, the IETF's approach is one of maximum reuse: only the SIP protocol is...