Uri Dialing And Firewall Traversal - Cisco TelePresence Administrator's Manual

How you add the DNS records depends on the type of DNS server you are using. Instructions for setting up
two common DNS servers are given in the
For locally registered H.323 endpoints to be reached using URI dialing, either:
the H.323 endpoints should register with the VCS using an address in the format of a URI
n
an appropriate transform should be written to convert URIs into the format used by the H.323 registrations.
n
An example would be a deployment where H.323 endpoints register with an alias, and incoming calls are
made to alias@domain.com. A local transform is then configured to strip the @domain, and the search is
made locally for alias. See
this.
SIP endpoints always register with an AOR in the form of a URI, so no special configuration is required.
Several mechanisms could have been used to locate the VCS. You may want to enable calls placed to
user@<IP_address> to be routed to an existing registration for user@example.com. In this case you
would configure a pre-search transform
replace it with the suffix of example.com.

URI dialing and firewall traversal

If URI dialing via DNS is being used in conjunction with firewall traversal, DNS zones should be configured
on the VCS Expressway and any VCSs on the public network only. VCSs behind the firewall should not have
any DNS zones configured. This will ensure that any outgoing URI calls made by endpoints registered with
the VCS will be routed through the VCS Expressway.
In addition, the DNS records for incoming calls should be configured with the address of the VCS
Expressway as the authoritative gatekeeper/proxy for the enterprise (the
section for more information). This ensures that incoming calls placed using URI dialing enter the enterprise
through the VCS Expressway, allowing successful traversal of the firewall.
Cisco VCS Administrator Guide (X7.1)
DNS configuration examples
Stripping @domain for dialing to H.323 numbers
that would strip the IP_address suffix from the incoming URI and
Dial plan and call processing
section.
for an example of how to do
DNS configuration examples
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