Cisco Catalyst 3000, Administration Manual

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In Redirect by Application configuration, the SIP trunk passes the control to Redirecting Application layer
for handling the rerouting. The Rerouting Calling Search Space configured on SIP trunk is passed to allow
further check on class of service and privilege of the calling user for redirection to the new Contact. To set
these parameters, refer to
Connection Type: SIP Trunk, on page 283 .
The Redirect by Application feature of the SIP trunk allows the Cisco Business Edition 3000 to do the
following:
• Apply digit analysis to the redirected contacts to ensure that the calls are routed correctly
• Prevent DOS attack by limiting the number of redirection (recursive redirection) that a service parameter
can set
• Allow other features to be invoked while the redirection is taking place
Calls get redirected to a restricted phone number (such as an international number) due to handling redirection
at the stack level to route the calls without blocking. This behavior occurs when the Redirect by Application
check box is not checked in the Cisco Business Edition 3000 Administrative Interface.
In case of multiple redirections before final redirection over SIP trunk, the maximum of two Redirection
headers will be sent over SIP trunk, that is the original called party and last called party information. Note
Incoming OOD REFER Message Handling
Out-of-dialog REFER (OOD-R) enables remote applications to establish calls by sending a REFER message
to Cisco Business Edition 3000 without an initial INVITE. After the REFER is sent, the remainder of the call
setup is independent of the application and the media stream does not flow through the application. The
application using OOD-R triggers a call setup request that specifies the Referee address in the Request-URI
and the Refer-Target in the Refer-To header.
Cisco Business Edition 3000 handles the incoming REFER from a SIP trunk service provider.
Calling search spaces determine the partitions that calling devices can search when they attempt to complete
a call. The out-of-dialog calling search space is used when a Cisco refers a call (B) that is coming into SIP
user (A) to a third party (C) when no involvement of SIP user (A) exists. In this case, the system uses the
out-of-dialog calling search space of SIP user (A). The third party (C) is either an internal extension or an
auto attendant client.
CUBE on Cisco ISR8xx, the session border element in the Cisco Business Edition 3000 SIP trunking solution,
does not support the OOD REFER inter-operability. The service provider cannot send OOD REFER through
CUBE on Cisco ISR8xx through Cisco Business Edition 3000.
Calling Party Transformation
The mid-call SIP messages, namely reINVITEs, UPDATE or 200 OK sent from the calling party direction
on SIP Trunk from Cisco Business Edition 3000, carry the URI identity containing a number in user portion.
This occurs during Hold/Resume and Transfer, which results in transactions inside a SIP dialog.
By default, the Cisco Business Edition 3000 sends configured extension number only, while expected number
for inter-operability with the SIP service provider is the DID or full number (for example: Office code +
Subscriber code).
The Cisco Business Edition 3000 preconfigures the Calling party Transformation on SIP Trunk used to connect
to the session border elements.
Administration Guide for Cisco Business Edition 3000, Release 8.6(4)
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Common Configuration Concepts in Cisco Business Edition 3000