When talking about Dial Plan and Digit Manipulation Cisco Unified Communication Manager, three components play an important role to perform the transformation of the calling and called parties.
The Translation Pattern, Transformation Pattern and Route Pattern have a common word which is “Pattern”, the Pattern in the three components is checked by the CUCM to find a match of the Called Number when receiving a Call.
The priority to apply which component depends on the configuration of CSS and Partition, through the 4 use cases and examples below you will see when the translation pattern or transformation pattern or route pattern is applied first.
Case 1:
The Phone-2 will ring because when we have equals match in this case a Translation Pattern and a Route Pattern then CUCM uses higher Partition in CSS (the Partition listed first). In this case CLACCM-PT is higher than CLCOR-PT so it will match the Route Pattern and will routes the call. So the Phone-2 will ring because the RP is listed first in the partitions list.
Case 2:
The Phone-2 will not ring. The Called Transformation Pattern is applied after the route-pattern decision and after the Gateway or SIP Trunk Selection. Here what happen, the Phone-1 CSS has access to the Called Transformation Pattern Partition, this Partition is listed first, the result is that there is a blackhole. and the call will not be routed.
Case 3:
Phone-2 will not ring. There are two sources of the call, Phone-1 and the FIRST translation pattern TP-1, the Use Originator CSS option in the second translation pattern TP-2 means that the CUCM will use the CSS of the phone, even if from the second translation pattern’s perspective, the call comes from the first translation pattern.
Case 4:
The Phone-2 will ring, Called Number 811002 hits the Translation Pattern TP-1, the TP-1 translates the Called Number to 911002 and it has the CSS-2 that includes the Partition PT-3 of the second Translation Pattern TP-2, the new Called Number 911002 hits the TP-2, which uses originators CSS and Phone-1 has a PT-4 in its CSS-1. That allows Phone-1 to call Phone-2.