On Cisco Unified CM, multiple points and levels are availables to do Digits Manipulation, offering more granularity and flexibility, especially for outbound calls, the Called or the Calling parties can be manipulated using a Translation Pattern, Route Pattern, Route Group under the Route List Details or at the SIP Trunk/Gateway with a Transformation Pattern. The question that arises what if different Digits Manipulation are involved at different level? How the Cisco Unified CM behaves and manipulates the Called Party for example?
First, Digit Manipulation of the Route List overrides any transformation in the Route Pattern, later a Transformation Pattern overrides the Digits Manipulation of the Route Pattern and the Route List.
Another question that we can ask, if we have all the components involved for Digits Manipulation, which Called Number is used to find a match when calls reaches the Route List or the Transformation Pattern? original Called Number or the Transformed Number.
To answer the question with clarification, let's take an example.
jdoe dials 4001, the translation pattern 4XXX is matched and performs digits manipulation for the Called Party, the Called Number is transformed to 5001. The new Called Number 5OO1 matches the Route Pattern, at this level, a new transformation of the Called Party is applied, now the new Called Number is 6001. The Route Pattern points to the Route List, in the Route List Details, there is a Route Group configured with Called Party Mask X1XX, the Route List overrides the transformation performed at the Route Pattern level but when applying the Called Party Mask configured in the Route Group, the digits manipulation is performed based on the ORIGINAL Called Number.
If there is no Translation Pattern, the Mask X1XX is applied on the Called Number 4001, the one dialed by the jdoe user.
Since a Translation Pattern is involved and transforms the Dialed Number 4001 to 5001, at this point, the Route List and later the Called Party Transformation Pattern under the SIP Trunk consider 5001 as the original Called Number, NOT 4001.
As the result, the Mask configured at the Route List Details X1XX is applied for the number 5001 and becomes 5101.
Now when the call reaches the SIP Trunk, there are multiple Called Party Transformation Pattern. At this point, as mentioned previsouly.
If the Translation Pattern didnt exist, the Called Party Transformation Pattern is applied based on the original Called Number, the one dialed by jdoe user 4001, therefore the Transformation Pattern 4XXX would be applied and the new Called Number becomes 4141.
Since a Translation Pattern is involved to create a new Called Number which 5001. The Cisco Unified CM lookup a Transformation Pattern that matches the number 5001. In this scenario, the Transformation Pattern 5XXX is applied and transforms the Called Number 5001 to 5151.
When the call will egress the SIP Trunk, the SIP INVITE is sent with a Called Party 5151.
