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External Phone Number Mask

The external phone number mask is a directory number (DN) configuration attribute. The external phone number mask is leveraged in call routing to manipulate the internal directory number to digits that can be routed over the PSTN. The external phone number mask is configured on the Directory Number configuration page in CUCM Administration. The use of the external phone number mask is enabled in the route list detail calling party number digit manipulations. The external phone number mask can also be leveraged at the route pattern, translation pattern, calling party transformation pattern, and hunt pilot configurations. Automated alternate routing (AAR) uses the external phone number mask to change the internal dial plan into a PSTN-routable dial plan when rerouting intersite calls from the WAN to the PSTN. The external phone number mask of the first DN of the phone is also used for the following functions:

  • To change the display of the main phone number at the top of the LCD screen. A DN of 15001 with an external phone number mask of 21255XXXXX would result in a displayed phone number of 2125515001. Any user on the phone can instantly identify his PSTN direct inward dialing (DID) number by viewing the LCD of the phone.
  • AAR technology uses the external phone number mask to manipulate digits for PSTN outbound dialing when bandwidth is not available for a guaranteed-quality call over the WAN (CAC). The AAR call will be rerouted out the PSTN using the full PSTN phone number of the destination as determined by the application of the external phone number mask.
  • To change the display of the caller ID for all calls in which the call classification is Off-Net. The calling party number (caller ID) is changed to the full ten-digit DID phone number of the calling party.

Figure 11-4 displays the configuration of the external phone number mask at the Directory Number Configuration page. This page is accessed by navigating to the following in CUCM Administration:

Step 1. Choose Device > Phone.

Step 2. Insert the search criteria and click the Find button.

Step 3. Click the phone that has the required directory number (DN).

Step 4. Click the directory number.

Figure 11-4

Figure 11-4 Directory Number Configuration: External Phone Number Mask

Figure 11-5 displays the configuration option that is normally used at the route list detail level. The Calling Party Transformations section includes a check box to use the calling party's external phone number mask for the calling party presentation on the PSTN. This same option can be seen in various call-routing configuration elements.

Figure 11-5

Figure 11-5 Route Pattern Configuration: External Phone Number Mask

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