The development of a national dial plan is an involved process. Fortunately, Cisco CallManagers deployed in North America can make use of the @ symbol to represent the various patterns that make up the North American Numbering Plan (NANP). In this document, the @ symbol is referred to as a macro as it represents multiple patterns. This document explains how the @ macro works and also how to use the route filters.
The variable length patterns that the @ wildcard and the NANP covers are as follows:
Emergency number 911
Other service numbers
Toll free numbers
Readers of this document should be knowledgeable of the following:
The information in this document is based on these software versions:
The information presented in this document was created from devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If you are working in a live network, ensure that you understand the potential impact of any command before using it.
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Follow these instructions to configure the route pattern.
Note: Typically in the U.S., corporate users dial 9 to get an outside line and expect a secondary dial tone.
In the Cisco CallManager Administration page, go to Route Plan > Route Pattern. Click Add a New Route Pattern. You will see this screen:
Note: For Cisco CallManager 4.x, go to Route Plan > Route Pattern/Hunt Pilot > Add a New Route.
Enter 9.@ in the Route Pattern field and select PreDot from the Discard Digits drop-down menu at the bottom of the page in the Called Party Transformations section.
By doing this, you will not forward the leading 9 to the PSTN. The Discard Digit instructions will vary depending upon many factors, including gateway selection and dial peer configuration, if applicable.
Make sure you select the Gateway/Route list that will enable access to the outside.
Check the Provide Outside Dial Tone box if you want to hear a secondary dial tone after dialing the leading 9 and click Insert.
Note: For more information regarding the route filter, see the Route Filter Configuration: Restricting Some Calls From the NANP section of this document.
In the configuration in the last section, a user would have to dial the preceding 9 before dialing 911. However, another route pattern can be added for only 911, so that in case a user does not dial the preceding 9, the call will still be connected. You can add this second route pattern for 911 (without the leading 9), as shown in the screen below.
Enter 911 in the Route Pattern field.
Select the appropriate Gateway/Route List to reach the Telco.
Make sure that Discard Digits is set to <None>, as we want to send all the digits to the PSTN in this case.
An important point to remember is that the @ wildcard will give you access to every pattern covered under the NANP. To manipulate access and restrictions to different numbers, a basic knowledge of the NANP and route filter is important. To understand how route filters work, let's take an example.
Note: Assume that the @ pattern covers the route patterns below.
| Route Pattern
|| 411, 911
| [2-9]XX[2-9]XX XXXX
|| 10-digit dialing
|| LOCAL-AREA-CODE OFFICE CODE SUBSCRIBER
| 01 1 3[0-469]!
|| International dialing
|| INTERNATIONAL-ACCESS INTERNATIONAL-DIRECT-DIAL COUNTRY-CODE NATIONAL-NUMBER
If no route filter is specified in the route pattern configuration, all the above route patterns will be part of the 9.@ route pattern. However, if you wish to deny access to, for example, international numbers, you must use a route filter that denies the clause International-Access and then applies this route filter to the route pattern 9.@. In the route filter configuration, a clause exists for every dial plan that is part of the NANP. You can explicitly add or deny them according to your need.
Follow the steps below to configure the route filter.
Go to Router Plan > Route Filter > Add a New Route Filter.
Choose North American Numbering Plan as your dial plan and give the route filter a name, as in the screen below.
In this route filter, chose the value "DOES-NOT-EXIST" for the clause International-Access. Once you apply the route filter to the route pattern, all international calls will be blocked. To better understand every clause and its impact, use the Help > For this page link from the top menu when you are on the route filter configuration page.
Note: If you are not in North America, or you need some other special dial plan, study the dial plan of your country using the guidelines specified in Supporting Variable Length Dial Plans for CallManager Route Patterns - an Exercise in Designing a Route Pattern that Covers a National Dial Plan in case you do not want to use the ! wildcard to match all variable length patterns.
For internationalized dial plans you can download the installation file from International Dial Plan Software Downloads (registered customers only) and install the one you need on your Cisco CallManager to provide a unique numbering plan specific to countries outside of North America.