Asterisk - The Open Source Telephony Project  18.5.0

DUNDi is a peer-to-peer system for locating Internet gateways to telephony services. Unlike traditional centralized services (such as the remarkably simple and concise ENUM standard), DUNDi is fully-distributed with no centralized authority whatsoever.

DUNDi is not itself a Voice-over IP signaling or media protocol. Instead, it publishes routes which are in turn accessed via industry standard protocols such as IAX, SIP and H.323.