CUCM Transformation Masks

Dialing transformations allow the call-routing component to modify either the calling (initiator) or called (destination) digits of a call. Transformations that modify the calling number (automatic number identification, ANI) are calling-party transformations; transformations that modify the dialed digits (dialed number identification system, DNIS) are called-party transformations.

Transformation masks use mask operations that allow the suppression of leading digits, the modification or preservation of digits, and the insertion of digits.

A mask operation requires two pieces of information: the number to mask and the mask itself.

In the mask operation, CUCM overlays and aligns the number with the mask so that the last character of the mask aligns with the last digit of the number. CUCM uses the corresponding digit of the number wherever the mask contains an X. If the number is longer than the mask, the mask obscures the extra digits.

Figure 12-9 illustrates an approach typically used to change the ANI of internal callers when they make calls to the PSTN. In this example, the five-digit extension of 45000 is changed to a ten-digit pattern for the purposes of caller ID on the PSTN. Caller ID refers to the presentation of the calling-party name and number, whereas ANI refers only to the calling number. Caller ID is being used in this book to represent the presentation of the calling-party number. In the example, the mask applied to 45000 has changed the 45 of the calling party to 36, and five digits are prefixed before the number so that users connected to the PSTN can return phone calls to the presented number.

Figure 12-9 Transformation Mask Operation

Figure 12-9 Transformation Mask Operation

Figure 12-10 illustrates a process in which a ten-digit phone number is being changed into an internal five-digit extension. When a mask is applied to either a calling- or called-party number, the digits are matched from right to left. If a ten-digit pattern has a five-digit mask applied to it, the resulting number will include only five digits. The example is changing the 65 to a 45. If a digit is provided in a mask, it will override the original digits. The X character will allow the original digit to be preserved.

Figure 12-10 Transformation Mask Operation

Figure 12-10 Transformation Mask Operation

Transformation masks are configurable at route patterns, translation patterns, and route lists (per route group).

The calling- and called-party transformation settings that are assigned to route groups in a route list override the corresponding transformation settings that are assigned to a route pattern. Route-pattern transformations apply only when a route pattern is pointed directly to a gateway. Route patterns are normally pointed to a route list. Multiple route patterns can point to the same route list, but multiple route patterns cannot point directly to the same gateway. Inserting gateways into route groups allows the gateways to be used for many different route patterns.

Transformation masks are usually applied at the route-list level. In this way, a different transformation mask can be assigned for each route group in the route list.

Most calls between clusters of the same company have two route groups: a PSTN route group and an IP WAN route group. The IP WAN route group includes one or more intercluster or SIP trunks, and the PSTN route group may contain one or more gateways that connect to the PSTN. When CUCM uses a trunk from the IP WAN route group, CUCM forwards the internal extension number (five digits if the internal dial plan is using five-digit dialing). When CUCM forwards a call to a gateway in the PSTN route group, the network administrator applies a mask that transforms the number into an E.164-compliant phone number that can be routed over the PSTN.

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  • leah schmitt
    How to set up CUCM to accept both 10 digit and 11 digit called party transform mask?
    7 months ago
  • linda
    How to mask cucm translated number?
    2 months ago

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