7.3. Utopia: Setting up global IP telephony
To set up an infrastructure to provide address resolution for
international addresses that supports H.323 and SIP not all of the
protocols described in Section 7.1 are useful.
- H.323 LRQs - Among other reasons this
solution is not suitable because it does not support SIP.
- H.225.0 Annex G - Does not support SIP.
- TRIP - Supports H.323 and SIP but
can be used for telephone numbers only.
- ENUM + SRV-Records - Supports SIP and
H.323 and can be easily configured to support more protocols. Does
not impose a network of peer relationships because of it
decentralized nature. Supports URIs and telephone numbers.
It is obvious, that the combined usage of ENUM for mapping telephone
numbers to URIs and SRV-Records to resolve URIs upon a well-understood
and scalable mechanism like DNS is an ideal solution to this problem.