62
D14049.05
February 2009
Grey Headline
(continued)
TANDBERG
VIDEO COMMUNICATIONS SERVER
ADMINISTRATOR GUIDE
Introduction
Getting started
Overview and
status
System
configuration
VCS
configuration
Zones and
neighbors
Call
processing
Bandwidth
control
Firewall
traversal
Appendices
Applications
Maintenance
Interworking
The VCS is able to act as a gateway between SIP and H.323, translating calls from one protocol to
the other. This is known as “interworking”.
By default, the VCS will act as a SIP-H.323 and H.323-SIP gateway but only if at least one of the
endpoints is locally registered. You can change this setting so that the VCS will act as SIP-H.323
gateway regardless of whether the endpoints involved are locally registered. You also have the
option to disable interworking completely.
When searching for an alias, the VCS will first search all the highest-priority zone(s) using
the protocol of the incoming call. If the search was unsuccessful the VCS may then search
the same zone(s) again using the alternative protocol, depending on where the search came
from and the
Interworking mode
(
VCS configuration > Protocols > Interworking
). If that search was
unsuccessful, the VCS will then move on to the next highest priority zones, searching first in the
native protocol and then in the alternative protocol.
If the request has come from a neighboring system and
Interworking mode
is set to
RegisteredOnly
,
the VCS will search the local zone using both protocols, and all other zones using the native
protocol only (because it will interwork the call only if one of the endpoints is locally registered).
If
Interworking mode
is set to
On
, or the request has come from a locally registered endpoint, the
VCS will search the local zone and all external zones using both protocols.
Calls for which the VCS is acting as an SIP to H.323 gateway are traversal calls. They will
therefore require a traversal call licence.
Overview
Configuring interworking
The
Interworking
page allows you to allows you to determine whether or not the VCS will act as a
gateway between SIP and H.323 calls.
To go to the
Interworking
page:
VCS configuration > Protocols > Interworking
•
To configure interworking using the CLI:
xConfiguration Interworking Mod
•
e
H.323 <-> SIP interworking mode
The options for this setting are:
Off
: the VCS will not act as a SIP-H.323 gateway.
RegisteredOnly
: the VCS will act as a SIP-H.323 gateway but only if at least one of the endpoints is
locally registered.
On
: the VCS will act as SIP-H.323 gateway regardless of whether the endpoints are locally
registered.
!
We recommend that you leave this setting as
RegisteredOnly
(where calls are interworked
only if at least one of the endpoints is locally registered). Unless your network is correctly
configured, setting it to
On
(where all calls can be interworked) may result in unnecessary
interworking, for example where a call between two H.323 endpoints is made over SIP, or vice
versa.
Enabling SIP endpoints to dial H.323 numbers
SIP endpoints can only make calls in the form of URIs - e.g.
name@domain
. If the caller does not
specify a domain when placing the call, the SIP endpoint will automatically append its own domain
to the number that is dialed. So if you dial
123
from a SIP endpoint, the search will be placed for
123@domain
. If the H.323 endpoint being dialed is just registered as
123
, then the VCS won't be
able to locate the alias
123@domain
and the call will fail.
The solutions are to either:
Ensure all your endpoints, both H.323 and SIP, register with an alias in the form
1.
name@domain
.
Create a pre-search transform on the VCS that strips the
2.
@domain
portion of the alias for those
URIs that are in the form of
number@domain
.
Refer to the
Pre-search transforms
section for information on how to configure pre-search
transforms, and to
Stripping @domain for dialing to H.323 numbers
for an example.
