Use the subexpression builder to build complex rule conditions from subexpressions by using AND, OR, NOT and parenthetical grouping. The subexpression builder validates the rule when you apply the changes, and alerts you to mismatched parentheses, and unsupported logic operators.
To view this page, click Servers > On demand routers > odr_name > SIP on demand router properties > Routing policy SIP rules > Specify by > Expression > Subexpression builder.