AudioCodes Mediant 4000 SBC User Manual page 458

CHAPTER 19 Coders and Profiles
Parameter
'Remote 3xx Mode'
sbc-rmt-3xx-behavior
[IpProfile_
SBCRemote3xxBehavior]
Description
Defines the device's handling of SIP 3xx redirect
responses for the SIP entity associated with the IP Profile.
By default, the device's handling of SIP 3xx responses is
to send the Contact header unchanged. However, some
SIP entities may support different versions of the SIP 3xx
standard while others may not even support SIP 3xx.
When enabled, the device handles SIP redirections
between different subnets (e.g., between LAN and WAN
sides). This is required when the new address provided by
the redirector (Redirect sever) may not be reachable by the
far-end user (FEU) located in another subnet. For example,
a far-end user (FEU) in the WAN sends a SIP request via
the device to a Redirect server in the LAN, and the
Redirect server replies with a SIP 3xx response to a PBX
in the LAN in the Contact header. If the device sends this
response as is (i.e., with the original Contact header), the
FEU is unable to reach the new destination.
■ [0] Transparent = (Default) The device forwards the
received SIP 3xx response as is, without changing the
Contact header (i.e., transparent handling).
■ [1] Database URL = The device changes the Contact
header so that the re-route request is sent through the
device. The device changes the URI in the Contact
header of the received SIP 3xx response to its own URI
and adds a special user prefix ("T~&R_"), which is then
sent to the FEU. The FEU then sends a new INVITE to
the device, which the device then sends to the correct
destination.
■ [2] Handle Locally = The device handles SIP 3xx
responses on behalf of the dialog-initiating UA and
retries the request (e.g., INVITE) using one or more
alternative URIs included in the 3xx response. The
device sends the new request to the alternative
destination according to the IP-to-IP Routing table (the
'Call Trigger' field must be set to 3xx).
■ [3] IP Group Name = If the 'SIP Group Name'
parameter of the IP Group of the dialog-initiating UA is
configured with a non-empty value, the device changes
the host part of the Contact header in the 3xx response
to this value, before forwarding the 3xx response to the
dialog-initiating UA.
■ [4] Local Host = The device changes the host part of
the Contact header in the 3xx response before
forwarding the 3xx response to the dialog-initiating UA.
If the 'Local Host Name' parameter of the IP Group of
the dialog-initiating UA is configured with a non-empty
value, the device changes the host part of the Contact
header to this value. If the 'Local Host Name' is empty,
the device changes the host part to the device's IP
address (the same IP address used in the SIP Via and
Contact headers of messages sent to the IP Group).
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Mediant 4000 SBC | User's Manual