CUCM Call Routing (part 4): International calls

In the last blog, we discussed 11-digit phone numbers that carry International tariffs. These route patterns can be removed from the Cisco Unified Communications Manager (CUCM) dial plan by configuring individual route patterns with a Block This Route Pattern condition. Each route pattern to be specified was in the last blog entry.

This brings us to International dialing. In the United States, International calls require the International operator code of 011 to be dialed. The 9.011! and 9.011!# route patterns are required for International route patterns. The exclamation point (!) matches on one or more digits which is perfect for variable length International dialing. After the 011 International operator code, there will be a two digit country code, but country dial plans vary wildly from the NANP. Since CUCM does not know how many digits to wait for with the exclamation point, the user must wait for the T.302 inter-digit timeout to expire which is 15 seconds by default. The pound (#) key will terminate the inter-digit timeout and force the CUCM server to attempt to route the call. The call will be routed and the end user will hear ring back or the call will be rejected and the end user will hear reorder tone (fast busy).

The @ symbol is a wildcard used in CUCM to allow any call within the North American Numbering Plan (NANP). The @ symbol includes the entire NANP dial plan discussed in the past few blogs. In addition, the @ symbol includes 1010 dialing (e.g. 10-10-321) which allows users to route calls through different service providers. Allowing 1010 dialing in an enterprise environment can lead to increased costs because most large enterprise have negotiated rates based on a guarantee of a certain number of long distance minutes per month. A large company has contracted a rate of 1 cent per minute (continental United States) based on a guarantee of 1 million minutes per month. The company will need to pay for 1 million minutes per month whether they use them or not.

The 9.@ route pattern can be used to remove entries from the dial plan if a route filter is applied to it. The route filter clauses would need to be configured first and then applied to the route pattern including the @ wild card. Area Code == 900 is an example of a route pattern clause.

The next blog entry will explain the Route Pattern, Route List, Route Group, Gateway/Trunk call routing logic.

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