AudioCodes Media 800 MSBR

User's Manual 442 Document #: LTRT-12809
Mediant 800 MSBR
2. If the message is received without an Authorization header, the device "challenges"
the client by sending a 401 or 407 SIP response. The client then resends the request
with an Authorization header (containing the user name and password).
3. The device validates the SIP message according to the settings of the parameters,
AuthNonceDuration, AuthChallengeMethod and AuthQOP.
• If validation fails, the message is rejected and the device sends a 403
"Forbidden" response.
• If validation succeeds, the device verifies identification of the SBC user. This is
done by checking that the user name and password received from the user is the
same username and password that appears in the device's database. The SBC
users in the database are obtained from the User Information file. If the SIP SBC
user is not successfully authenticated after three attempts, the device sends a
403 "Forbidden" response.
4. If the user is successfully identified, the SIP message request is processed.
30.8 Interworking SIP Signaling
The device supports interworking of SIP signaling messages to ensure interoperability
between communicating SIP UAs or entities. This is critical in network environments where
the UAs on opposing SBC legs have different SIP signaling support. For example, some
UAs may support different versions of a SIP method while others may not event support a
specific SIP method. The configuration method for assigning specific SIP message
handling modes to UAs, includes configuring an IP Profile with the required interworking
mode, and then assigning the IP Profile to the relevant IP Group.
This section describes some of the device's support for handling SIP methods to ensure
interoperability.
30.8.1 Interworking SIP 3xx Redirect Responses
The device supports interworking of SIP 3xx redirect responses. By default, the device's
handling of SIP 3xx responses is to send the Contact header unchanged. However, some
SIP UAs may support different versions of the SIP 3xx standard while others may not even
support SIP 3xx.
The handling of SIP 3xx can be configured for all calls, using the global parameter
SBC3xxBehavior. For configuring different SIP 3xx handling options for different UAs (i.e.,
per IP Group), use the IP Profile table parameter, 'SBC Remote 3xx Behavior'.
30.8.1.1 Resultant INVITE Traversing Device
The device can handle SIP 3xx responses so that the new INVITE message sent as a
result of the 3xx traverses the device. The reasons for enforcing resultant INVITEs to
traverse the device may vary:

The user that receives the 3xx is unable to route to the 3xx contact (i.e., the user is on
the LAN and the new contact is on the WAN). In such a scenario, the device enables
the user to reach the WAN contact and overcome NAT problems.

Enforce certain SBC policies (e.g., call admission control, header manipulation, and
transcoding) on the resultant INVITE.