AudioCodes Mediant 500 E-SBC, User Manual

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User's Manual 18. SIP Definitions
Version 6.8 289 Mediant 500 E-SBC
18.4 Configuring SIP Message Manipulation
The Message Manipulations table lets you configure up to 100 Message Manipulation
rules. A Message Manipulation rule defines a manipulation sequence for SIP messages.
SIP message manipulation enables the normalization of SIP messaging fields between
communicating network segments. For example, it allows service providers to design their
own policies on the SIP messaging fields that must be present before a SIP call enters
their network. Similarly, enterprises and small businesses may have policies for the
information that can enter or leave their networks for policy or security reasons from a
service provider. SIP message manipulations can also be implemented to resolve
incompatibilities between SIP devices inside the enterprise network.
Each Message Manipulation rule is configured with a Manipulation Set ID. You can create
groups (sets) of Message Manipulation rules by assigning each of the relevant Message
Manipulation rules to the same Manipulation Set ID. The Manipulation Set ID is used to
assign the rules to specific calls.

SBC application: Message manipulation rules can be applied pre- or post-
classification:
•
Pre-classification Process: Message manipulation can be done on incoming
SIP dialog-initiating messages (e.g., INVITE) prior to the classification process.
You configure this by assigning the Manipulation Set ID to the SIP Interface on
which the call is received (see Configuring SIP Interfaces on page
259 ).
•
Post-classification Process: Message manipulation can be done on inbound
and/or outbound SIP messages after the call has been successfully classified.
You configure this by assigning the Manipulation Set ID to the relevant IP Group
in the IP Group table (see Configuring IP Groups on page
263 ).

Gateway application: Message Manipulation rules are applied to calls as follows:
•
Manipulating Inbound SIP INVITE Messages: Message manipulation can be
applied only to all inbound calls (not specific calls). This is done by assigning a
Manipulation Set ID to the "global" ini file parameter,
GWInboundManipulationSet.
•
Manipulating Outbound SIP INVITE Messages:
a. Message manipulation can be done for specific calls, by assigning a
Manipulation Set ID to an IP Group in the IP Group table, using the
'Outbound Message Manipulation Set' parameter.
b. Message manipulation can be applied to all outbound calls (except for IP
Groups that have been assigned a Manipulation Set ID). This is done by
assigning a Manipulation Set ID to the "global" ini file parameter,
GWOutboundManipulationSet.
The device also supports a built-in SIP message normalization feature that can be enabled
per Message Manipulation rule. The normalization feature removes unknown SIP message
elements before forwarding the message. These elements can include SIP headers, SIP
header parameters, and SDP body fields.
The SIP message manipulation feature supports the following:

Manipulation on SIP message type (Method, Request/Response, and Response type)

Addition of new SIP headers

Removal of SIP headers ("black list")

Modification of SIP header components such as values, header values (e.g., URI
value of the P-Asserted-Identity header can be copied to the From header), call's
parameter values

Deletion of SIP body (e.g., if a message body is not supported at the destination
network this body is removed)

Translating one SIP response code to another

Topology hiding (generally present in SIP headers such as Via, Record Route, Route