D 14049.01
07.2007 82
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
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Introduction Getting
Started
System
Overview
System
Configuration
H.323 & SIP
Configuration
Registration
Control
Zones and
Neighbors
Call
Processing
Firewall
Traversal
Bandwidth
Control Maintenance Appe ndices
TANDBERG
ADMINISTRATOR GUIDE
TANDBERG VIDEO COMMUNICATION SERVER
ADMINISTRATOR GUIDE
Call
Processing
URI Dialing
URI Dialing for Outgoing Calls
Process
When a user places a call using URI dia ling, they will typically dial an a ddress in the form name@
example.com from their endpoint. B elow is the process that is follo wed when a URI address is
dialed from an endpoint registe red with your VCS:
The VCS will check its own list of regis trations, and those of its Alte rnates, to see if the
address is registered locally.
If the address is not registered lo cally, the VCS will check all its zones to s ee if any of them are
configured with either:
an AlwaysMatch, or
a PatternMatch with a patt ern that matches the URI addr ess.
These zones will then be queried i n priority order for the UR I.
If one or more of the zones that cont ain a match are neighbor zones, th e neighbor will be
queried for the URI. If the neigh bor supports URI dialing , it may route the call itself.
If one or more of the zones that cont ain a match are DNS zones, this will tri gger the VCS to
attempt to locate the endpoin t through a DNS lookup. It does th is by querying the DNS ser ver
configured on the VCS for the lo cation of the domain as per the DN S resolution process.
If the domain part of the URI ad dress was resolved successf ully using an H.323 Location SRV
record (i.e. for _ h323ls) then the address returned is querie d via an LRQ for the full URI
address.
If the domain part of the URI ad dress was resolved using an H.323 Ca ll SRV record (i.e. for
_ h323cs) or an A/AAAA record lookup then the ca ll is routed directly to the IP ad dress
returned in that record. An exce ption to this is where the origin al dial string has a port
specified (e.g. user@example.com:1720) in which case the address returned is queried via
an LRQ for the full URI address.
If the domain part of the URI ad dress was resolved successf ully using a SIP SRV record (i.e. for
_ sip) then the request is forwarded to th e address returned.
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Configuring Matches for DNS Zones
If you wish locally registered en dpoints to be able to place URI cal ls via the VCS, then at a
minimum you should configure a DN S zone with a match that has a Mode of A lwaysMatch. This
will result in DNS always being quer ied, but will mean it is queried for al l aliases, not just URI
addresses.
To filter the queries sent to the DNS ser ver:
configure a DNS zone with a match t hat has a Mode of PatternMat ch
use the Pattern string and Pa ttern type fields to def ine the aliases that will trig ger a DNS query.
For example, a match with a Patter n string of *@* and a Pattern type of Regex will m ean that DNS
is only queried for aliases in the for m of typical URI addresses .
To set up further filters, confi gure the remaining matches in th e same DNS zone. You don’t need
to create new DNS zones unless you want t o configure more than the max imum of 5 matches.
You should create separate DNS zones if y ou want to filter based on the prot ocol (SIP or H.323) or
hop count to be used.
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