AudioCodes Mediant 800B User Manual page 296

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 (Trunk Groups, 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 been crossed. For Trunk Groups, the
device reports when the trunk's physical state indicates that the trunk is unavailable.

Credentials for Authentication: The Routing Server can provide user (e.g., IP Phone
caller) credentials (username-password) in the Get Route response, which can be used by
the device to authenticate outbound SIP requests if challenged by the outbound peer, for
example, Microsoft Skype for Business (per RFC 2617 and RFC 3261). If multiple devices
exist in the call routing path, the Routing server sends the credentials only to the last device
("node") in the path.

QoS: The device can report QoS metrics per IP Group to the Routing server, which the
Routing server can use to determine the best route (i.e., QoS-based routing). For more
information, see Configuring QoS-Based Routing by Routing Server on page 297.

Call Preemption for Emergency Calls: If you enable call preemption for emergency calls
(e.g., 911) on the device, the routing server determines whether or not the incoming call is
an emergency call and if so, handles the routing decision accordingly (i.e., preempts a non-
emergency call if the maximum call capacity of the device is reached in order to allow the
emergency call to be routed). To enable call preemption for emergency calls, use the
parameter SBCPreemptionMode for SBC calls and CallPriorityMode for Gateway calls.

To configure routing based on Routing server:
1. For each configuration entity (e.g., IP Group) that you want routing done by the Routing
server, configure the entity's 'Used By Routing Server' parameter to Used:
2. Configure an additional Security Administrator user account in the Local Users table (see
'Configuring Management User Accounts' on page 79), which is used by the Routing server
(REST client) to log in to the device's management interface.
User's Manual
Figure 15-47: Configuring Entity to Use Routing Server
Mediant 800B Gateway & E-SBC
296 Document #: LTRT-10632