AudioCodes Mediant 4000 SBC User Manual page 279

User's Manual
The following figure provides an example of information exchange between devices and a
Routing server for routing calls:
Figure 15-48: Example of Call Routing Information Exchange between Devices and Routing
The Routing server can also manipulate call data such as calling name, if required. It can
also create new IP Groups and associated configuration entities, if necessary for routing.
Multiple Routing servers can also be employed, whereby each device in the chain path can
use a specific Routing server. Alternatively, a single Routing server can be employed and
used for all devices ("stateful" Routing server).
The device automatically updates (sends) the Routing server with its' configuration
topology regarding SIP routing-related entities (SRDs, SIP Interfaces, and IP Groups) that
have been configured for use by the Routing server. For example, if you add a new IP
Group and enable it for use by the Routing server, the device sends this information to the
Routing server. Routing of calls associated with routing-related entities that are disabled for
use by the Routing server (default) are handled only by the device (not the Routing server).
In addition to regular routing, the Routing server also supports the following:

Alternative Routing: If a call fails to be established, the device "closest" to the failure
and configured to send "additional" routing requests (through REST API -
"additionalRoute" attribute in HTTP Get Route request) to the Routing server, sends a
new routing request to the Routing server. The Routing server may respond with a
new route destination, thereby implementing alternative routing. Alternatively, it may
enable the device to return a failure response to the previous device in the route path
chain and respond with an alternative route to this device. Therefore, alternative
routing can be implemented at any point in the route path. If the Routing server sends
an HTTP 404 "Not Found" message for an alternative route request, the device rejects
the call. If the Routing server is configured to handle alternative routing, the device
does not make any alternative routing decisions based on its alternative routing tables.

Call Status: The device can report call status to the Routing server to indicate
whether a call has successfully been established and/or failed (disconnected). The
device can also report when an IP Group (Proxy Set) is unavailable, detected by the
keep-alive mechanism, or when the CAC thresholds permitted per IP Group have
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15. Services
Mediant 4000 SBC