CUCM uses translation patterns to manipulate digits before forwarding a call. A translation pattern normally requires another digit analysis attempt. Translation patterns and route patterns can be used to block patterns, but the default action is to attempt call routing.
Digit manipulation and translation patterns are used frequently in geographically distributed systems where office codes might not be the same for all locations. A uniform dialing plan can be created and translation patterns applied to accommodate the unique office codes at each location. Here are some additional examples where translation patterns can be leveraged:
- Security and operator desks (abbreviated dialing to PSTN locations enabling more productivity)
- Hotlines with a need for private line automatic ringdown (PLAR) functionality (security phones in elevators, phones used to access lab facilities, college campuses, financial trading markets, and so on)
- Extension mapping from a public to a private network
Translation patterns use route pattern style matching and transformation mask–based digit manipulation. The pattern resulting after the translation pattern is applied is then rerouted by the system, causing a second round of digit analysis. The new pattern can match another translation pattern where digit transformation can occur once again. Eventually, the call is routed to a device or blocked by CUCM. CUCM passes digits through translation patterns for only ten iterations to prevent call-routing loops. There are various call-routing loop-deterrent mechanisms that are in the system by default.
Figure 11-6 illustrates the operation of a translation pattern. A translation pattern matches the called party number in a similar manner to the matching of a route pattern. The primary difference between route patterns and translation patterns is that translation patterns do not have a final path selection destination (route list, gateway, or trunk). Translation patterns exist only to manipulate digits; they do not perform call routing.
Figure 11-6 Translation Patterns
To configure a translation pattern, navigate to Call Routing > Translation Pattern in CUCM Administration.
Figure 11-7 is a screen capture of a translation pattern configuration. The translation pattern identifies the dialed digit string to match and the calling or called party transformation settings that should be applied.
Figure 11-7 Translation Pattern Configuration
If the Block This Pattern radio button is selected, a cause code must be selected. Choose a value from the drop-down menu:
- No Error
- Unallocated Number
- Call Rejected
- Number Changed
- Invalid Number Format
- Precedence Level Exceeded
The transformation settings are not applicable if the Block This Pattern radio button is selected.
If the translation pattern contains an @ sign, a numbering plan and route filter can be selected to match certain number patterns of the selected numbering plan.
Translation patterns are processed as urgent priority by default. The Urgent Priority check box can be disabled beginning with CUCM 7.0. Prior versions of the product did not allow the urgent priority option to be disabled at the translation pattern configuration. An overlapping dial plan involving a translation pattern could result in call-routing issues. Translation patterns are ignored when performing analysis of the dial plan with the Dialed Number Analyzer (DNA) tool that is integrated into the Cisco Unified Serviceability web pages.
When the direct inward dialing (DID) range from the provider does not match the internal DN range, a translation pattern can be used to map the PSTN number to the internal DNs.
Figure 11-8 illustrates a scenario in which a company has a PSTN DID range of 408 555-1XXX, but the internal four-digit extensions use the four-digit range of 4XXX. The company uses a translation pattern that matches the assigned PSTN DID range of 408 555-1XXX. The called party transformation mask of 4XXX is applied to the translation pattern, resulting in a 4XXX called party number. CUCM applies the transformations and reanalyzes the resulting pattern. Eventually the call is routed to a device or explicitly rejected.
Figure 11-8 Translation Pattern Example
An additional translation pattern of XXXX with a called party transformation mask of 4111 can be used to route calls of unidentified internal extensions to the company operator. Many companies own large blocks of DID numbers that they are not currently using. Assume that the DN of 4333 no longer exists in the system because the person that had the phone number won the lottery and decided that he was not going to work anymore. Because of cost-cutting measures implemented, a replacement is not hired and the Cisco IP Phone is reused with a unique configuration for a different department. When a customer calls that user, the customer will receive a reorder tone unless a call forward unregistered (CFUR) number has been configured for the DN that receives the call. If a called party number of 408 555-1333 is received from the PSTN, the call will be routed to DN 4333. If a DN of 4333 no longer exists in CUCM, the generic XXXX translation pattern will be matched and the call is routed to the company operator at extension 4111. The company operator instructs the outside caller that the employee no longer works for the company and tries to assist the caller in resolving his issue.