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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
Overview
Calls can be placed from an endp oint
registered to the local VCS to an end point that
is not registered with any system in t wo ways:
using an H.323 URI (if the DNS system
has been appropriately conf igured). If URI
dialing is used, DNS is queried for a ca ll
signaling address and, if found, t he call is
placed to that address. (See URI Di aling
for details of how to configure the C all
Signaling SRV Record.)
dialing its IP address
However, it is sometimes undesirabl e for a
system to be allowed to place a call to an
IP address directly. Instead, you ma y want
a neighbor to place the call on beh alf of the
VCS, or not allow such calls at all. The VCS
allows you to configure this behavi or.
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An unregistered endpoint can c all an endpoint registered wi th the local VCS.
If there are no firewalls betwee n the unregistered endpoin t and the locally registered en dpoint, it is possible for the ca ller to place the call by dialing
the locally registered endp oint’s IP address. However, we do not recom mend that callers are given IP a ddresses to use as the call may not alw ays be
successful (for example if the IP a ddress is private).
Instead, we recommend that call ers from unregistered endp oints dial the IP address or th e domain name (if configured) of t he local VCS, prefixed by
the alias they wish to call. The VCS will the n resolve the alias and place the c all as normal.
An unregistered endpoint is any d evice that
is not registered with an H.323 gatekee per
or SIP Registrar (e.g. VCS, gatekeepe r or
Border Controller). Althou gh most calls are
made between endpoints ea ch registered with
such a system, it is sometimes nece ssary
to place a call to, or receive a call from, an
unregistered endpoint.
Calls to an Unregistered Endpoint
Recommended Configuration for
Firewall Traversal
When the VCS Border Controlle r is neighbored
with an internal VCS for firewall t raversal,
you should typically set Calls to u nknown IP
addresses to Indirect on the int ernal VCS and
Direct on the VCS Border Contr oller. When a
caller inside the firewall atte mpts to place a
call to an IP address outside the f irewall, it
will be routed as follows:
The call will go from the endpoint to t he
internal VCS with which it is regis tered.
Since the IP address being call ed is not
registered to that VCS, and its Calls to
unknown IP addresses setti ng is Indirect,
the VCS will not place the call direc tly.
Instead, it will query its neig hbor VCS
Border Controller to see if that s ystem is
able to place the call on the inter nal VCS’s
behalf.
The VCS Border Controller rec eives the
call and since its Calls to unknown I P
addresses setting is Direc t, it will make
the call directly to the called IP a ddress.
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About Unregistered Endpoints Calls from an Unregistered Endpoint
Calls to Unknown IP Addresses
Determines the way in which the VC S will manage calls to IP addresses w hich are not registered
with it or one of its neighbors.
Direct: A locally registered e ndpoint will be allowed to make the ca ll to the unknown IP address
without the VCS queryin g any neighbors. The call setup wo uld occur just as it would if the far e nd
were registered directly to th e local system.
Indirect: Upon receiving t he call the VCS will check to see if the I P address belongs to one of its
locally registered endpoin ts. If so, it will allow the call. If not, it will qu ery its neighbors for th e
remote address. If the neighb or’s configuration allows it to conn ect a call to that alias, the VCS
will pass the call to that neighbor f or completion.
Off: This will not allow any endpoi nt registered locally to the VCS to c all an IP address of any
system not also registered locall y to that VCS.
Calls to and from Unregistered EndpointsConfiguration
To configure the VCS’s behavior when
receiving a call for an IP addres s that is not
registered locally:
VCS Configuration > Calls
You will be taken to the Calls page.
xConfiguration Call Services
CallsToUnknownIPAddresses
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