Multiple transformations can take place when placing a phone call. External phone number masks instructs the call routing of CUCM to apply the external phone number mask to the calling party directory number (DN) to pass caller ID information when calls are routed across a gateway to the PSTN. The external phone number mask is applied on an individual line basis through the DN configuration.
Figure 11-23 illustrates the multiple levels of calling party manipulations that are possible if the company wants to change the calling party number information so that a call appears to be coming from a main support number instead of an end user's extension (DN). The DN of 35062 will appear as 214 713-5062 when calls are routed through a gateway if only the external phone number mask is applied to the DN. The X character in the external phone number mask will pass through the original digits, while any digit specified in the mask will override the original number. If a mask applies more digits than the original number, a larger number will result. If the mask applies less digits than the original pattern, a smaller pattern will result. A calling party transformation mask has been applied at the route list detail level that changes the calling party number.
Figure 11-24 is an example of called party modifications where the user dials the pattern 10-10-321 before her phone number in an effort to save the company money on the phone call. The route pattern of 9.@ was matched by the dialed digits of 9 10-10-321 1 808 555-1221. The called party digit discard instruction (DDI) was configured to remove the 10-10 dialing. The resulting number is applied to the called party transformation mask, which consists of ten X wildcard characters. The access code of 9 and long-distance code of 1 have also been removed from the dialed digits. An 8 is prefixed as a new access code because the call can be routed to another system like a traditional PBX where an 8 is required as an access code to route the call to the PSTN.
Figure 11-24 Called Party Digit Manipulation
Figure 11-25 is an example where the Cisco Unified Communications (UC) TAC support group in Richardson, Texas, is placing calls to Cisco TAC in San Jose, California. The corporate policy is to not allow direct calls to members of either support team. The calling and called party numbers will be manipulated to reflect the main hunt pilot used to distribute calls (call coverage) to support group members at each site:
- User A at extension 5062 dials 91234.
- The route pattern of 9.1XXX is matched against the dialed digits (called party).
- A DDI of PreDot is applied to the called party. The resulting called party number is 1234.
- A calling party transformation mask of X000 is applied to caller 5062.
- The caller ID at the destination will now appear as if the call were placed from the hunt pilot of 5000 in Richardson, Texas.
- A called party transformation mask of X000 is applied to the dialed digits. 1234 is applied to the mask, and the resulting number is 1000.
- San Jose receives a call destined for extension 1000 with a caller ID of extension 5000.
Figure 11-25 Complex Digit Manipulation
Three levels of digit-manipulation options are available for outbound calls:
- Digit manipulation that is configured on the route pattern (not used if the route pattern is routed to the route list)
- Digit manipulation that is configured at the route list detail level
- Digit manipulation that is configured by using a transformation CSS on the gateway/trunk or device pool
The three levels of digit manipulation are not cumulative. Only one level of digit manipulation will be applied. The hierarchy for these digit manipulations are as follows:
- Digit manipulation settings on the route pattern take effect only when the route list details do not have any defined digit manipulations. A transformation CSS applied at the gateway/trunk or device pool will also cause the digit manipulations applied at the route pattern level to be skipped.
- If the transformation CSS at the gateway or trunk matches, but the route list details have configured digit manipulations, the manipulations configured at the route list details are used. Route pattern digit manipulations are ignored.
- If any manipulation matches through a gateway or trunk transformation CSS, all other digit manipulations are ignored.