Cisco Cisco TelePresence Video Communication Server Expressway 관리 매뉴얼
Configuring SIP and H.323 interworking
The
Interworking
page (
Configuration > Protocols > Interworking
) lets you configure whether or not the
VCS acts as a gateway between SIP and H.323 calls. The translation of calls from one protocol to the other
is known as “interworking”.
is known as “interworking”.
By default, the VCS acts as a SIP–H.323 and H.323–SIP gateway but only if at least one of the endpoints
that are involved in the call is locally registered. You can change this setting so that the VCS acts as a SIP–
H.323 gateway regardless of whether the endpoints involved are locally registered. You also have the option
to disable interworking completely.
that are involved in the call is locally registered. You can change this setting so that the VCS acts as a SIP–
H.323 gateway regardless of whether the endpoints involved are locally registered. You also have the option
to disable interworking completely.
The options for the H.323 <-> SIP interworking mode are:
n
Off: the VCS does not act as a SIP–H.323 gateway.
n
Registered only: the VCS acts as a SIP–H.323 gateway but only if at least one of the endpoints is locally
registered.
registered.
n
On: the VCS acts as a SIP–H.323 gateway regardless of whether the endpoints are locally registered.
You are recommended to leave this setting as Registered only (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.
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.
. The VCS always takes the
media for SIP–H.323 interworked calls so that it can independently negotiate payload types on the SIP and
H.323 sides and VCS will re-write these as the media passes.
H.323 sides and VCS will re-write these as the media passes.
Also in a SIP SDP negotiation, multiple codec capabilities can be agreed (more than one video codec can be
accepted) and the SIP device is at liberty to change the codec it uses at any time within the call. If this
happens, because VCS is in the media path it will close and open logical channels to the H.323 device as the
media changes (as required) so that media is passed correctly.
accepted) and the SIP device is at liberty to change the codec it uses at any time within the call. If this
happens, because VCS is in the media path it will close and open logical channels to the H.323 device as the
media changes (as required) so that media is passed correctly.
Searching by protocol
When searching a zone, the VCS first performs the search using the protocol of the incoming call. If the
search is unsuccessful the VCS may then search the zone again using the alternative protocol, depending on
where the search came from and the Interworking mode. Note that the zone must also be configured with
the relevant protocols enabled (SIP and H.323 are enabled on a zone by default).
search is unsuccessful the VCS may then search the zone again using the alternative protocol, depending on
where the search came from and the Interworking mode. Note that the zone must also be configured with
the relevant protocols enabled (SIP and H.323 are enabled on a zone by default).
n
If the request has come from a neighboring system and Interworking mode is set to Registered only, the
VCS searches 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).
VCS searches 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).
n
If Interworking mode is set to On, or the request has come from a locally registered endpoint, the VCS
searches the Local Zone and all external zones using both protocols.
searches the Local Zone and all external zones using both protocols.
Enabling SIP endpoints to dial H.323 numbers
SIP endpoints can only make calls in the form of URIs — such as name@domain. If the caller does not
specify a domain when placing the call, the SIP endpoint automatically appends its own domain to the
number that is dialed.
specify a domain when placing the call, the SIP endpoint automatically appends 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, the VCS will not be able to locate the alias 123@domain and the call
will fail. The solutions are to either:
being dialed is just registered as 123, the VCS will not be able to locate the alias 123@domain and the call
will fail. The solutions are to either:
Cisco VCS Administrator Guide (X8.1)
Page 92 of 504
Protocols
Configuring SIP and H.323 interworking