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URI dialing
URI dialing via DNS for incoming calls
Example DNS record configuration
A company with the domain name
example.com
using URI addresses in the format user@example.com. The VCS hosting the domain has the FQDN
vcs.example.com.
Their DNS records would typically be as follows:
•
_ h323ls. _ udp.example.com
SRV record for
•
_ h323cs. _ tcp.example.com
SRV record for
•
example.com
NAPTR record for
returns
•
_ sip. _ tcp.example.com
and
•
_ sip. _ udp.example.com
and
_ sips. _ tcp.example.com
•
_ sip. _ udp.example.com
•
SRV record for
_ sip. _ tcp.example.com
•
SRV record for
_ sips. _ tcp.example.com
•
SRV record for
vcs.example.com
•
A record for
returns the IPv4 address of the VCS
vcs.example.com
•
AAAA record for
returns the IPv6 address of the VCS
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 Appendix
In order 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
•
an appropriate transform should be written to convert URIs into the format used by the H.323
registrations. 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 the section
dialing to H.323 numbers
for an example of how to do 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 wish 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
strip the
IP_address
suffix from the incoming URI and replace it with the suffix of example.com.
Overview and
Introduction
Getting started
status
D14049.05
February 2009
wants to enable incoming H.323 and SIP calls
vcs.example.com
returns
vcs.example.com
returns
vcs.example.com
returns
vcs.example.com
returns
vcs.example.com
returns
DNS
configuration.
Stripping @domain for
pre-search transform
that would
System
VCS
Zones and
configuration
configuration
neighbors
Recommended configuration
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 (see the Appendix
configuration). This ensures that incoming calls placed using URI dialing enter the enterprise
through the VCS Expressway, allowing successful traversal of the firewall.
Call
Bandwidth
processing
control
111
TANDBERG
VIDEO COMMUNICATIONS SERVER
Firewall traversal
Firewall
Applications
Maintenance
traversal
ADMINISTRATOR GUIDE
DNS
Appendices
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