In the left navigation pane, go to SIP > Message Manipulation > Message Rule Table.
To create a header rule:
In the left navigation pane, click the Rule Table entry to which you want to add a Header Rule.
From the Create Rule drop down box, select Header Rule.
This logical expression is evaluated in order to determine whether the rule should be applied or not. An empty expression is evaluated as unconditionally true.
Example Rule:
${1} && (${2} || ${3})
Click the Add/Edit button to launch the Condition Expression Builder. The Condition Expression Builder enables you to create logical expressions using an interactive interface.
Specifies whether or not the rule is enabled.
Specifies the whether the true evaluation of the expression is optional or mandatory. Optional means subsequent rules are applied if this rule fails, mandatory means subsequent rules are not applied if this rule fails.
Specifies the action applied to the header by this rule if the condition expression evaluates true.
Specifies the type of header referenced by this rule.
Specifies which of group of the same header to modify. This is only available awhen the header name is: Contact, Route, Record-Route, or History-Info.
Each type of SIP header varies in its content and structure. The Header Value field holds a value that is provided for the entire header rule, or it can be opened to update its various components in the sub-panels.