Configuring Sip Message Manipulation - AudioCodes Mediant 4000 SBC User Manual

18.3

Configuring SIP Message Manipulation

The Message Manipulations table lets you configure up to 625 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 then used
to assign the rules to specific calls:

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 319).
•
Post-classification Process: Message manipulation can be done on inbound
and/or outbound SIP messages after the call has been successfully classified.
Manipulation occurs only after the routing process - inbound message
manipulation is done first, then outbound number manipulation (see Configuring
IP-to-IP Outbound Manipulations on page 489), and then outbound message
manipulation. For viewing the call processing flow, see Call Processing of SIP
Dialog Requests on page 419. You configure this by assigning the Manipulation
Set ID to the relevant IP Group in the IP Groups table (see Configuring IP Groups
on page 326).
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
and Service-Route).

Configurable identity hiding (information related to identity of subscribers, for example,
P-Asserted-Identity, Referred-By, Identity and Identity-Info)

Multiple manipulation rules on the same SIP message

Apply conditions per rule - the condition can be on parts of the message or call's
parameters

Multiple manipulation rules using the same condition. The following figure shows a
configuration example where rules 1 and 2 ('Row Rule' configured to Use Previous
Condition) use the condition configured for rule 0 ('Row Rule' configured to Use
User's Manual 358
Mediant 4000 SBC
Document #: LTRT-41729