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How to use Dialogic DMG1000 Media Gateway with multiple primary DNs.

Issue:

Some customers require the ability to set up multiple pilot numbers to reach the DMG1000 Media Gateway. These configurations cause integrations problems when calls are placed directly to these alternate numbers from user station sets because the call ends up appearing as if it was a forwarded call instead of a direct call to access the system.

Solution Summary:
The DMG1000 Media Gateway offers a parameter in the web configuration GUI that allows you to set a single hunt group extension as the primary DN for the gateway This parameter name is named ‘Hunt Group Extension’ and can be found under the Telephony group of configuration options in the web GUI. When using a single access number this is the recommended method of configuration.

When the need arises to use more than one pilot number to access the gateway (as is sometimes needed when you wish to provide different numbers to different user types) you must make your modifications in the CPID parser configuration file to allow for these additional DNs to appear. 

Technical Discussion
For the purpose of this technote we will use the following scenario. A site using a Nortel Meridian 1 PBX wants to give guest users a different number to call directly into voice mail than is used by other users. The PBX admin has decided to use different extension numbers that are forwarded to the primary DN for the DMG1000 Media Gateway as these access points. Shown below is the topology:

 

Without making any modifications to the gateway configuration, the above topology will work, but each time one of the users calls into their respective direct access numbers the call with be presented to the gateway, and the gateway will present it to the application, where it will appear as a forwarded call. 

Some applications will accept this by allowing users to configure the voice mail system to be aware of the different called party numbers. This makes the application able to recognize that a call arriving for the destination of 2000 or 3000 in this case is really a direct call from a specific class of user, and act accordingly.

If the application is not configurable in this manner, then the gateway configuration needs to be changed to take these extra phantom numbers into account, and remove them before sending the call to the application. This configuration change can be made via the CPID web page in the gateway configuration.

Starting with DMG1000 Media Gateway Version 4.0 Service Update 4 (SU4) the ability to configure the CPID parser has been exposed to the user via the web GUI.

You can determine if your gateway has Service Update 4 installed by reviewing the information present on the Version page of the web interface, or by using the Version command avhailable via either the serial or telnet interfaces. Your gateway has the capabilities added by Service Update 4 as long as the gateway application version number is 4.0.68 or higher.

The configurable CPID parser is the engine used to collect calling party, called party, and reason data from the text of each of the gateways eight (8) PBX ports. This engine is driven by a configuration file that contains a list of rules. These rules follow a standard regular expression like syntax. For a more complete set of documentation regarding the configurable CPID parser please consult the Intel NetStructure DMG1000 Media Gateway users guide available at the link provided in the Related Documentation area of this technical note.

To access the configurable CPID configuration log into the gateway via the web interface, click on the 'CPID Parsing' item in the left column. On this page you will see a large text area that contains the rules currently being used by the parser engine.

At the top of the list of rules is an area with several translation rules already present. This is the area where you will be adding your new rules.

Before making any changes to the existing rules select everything in the text area, copy the text and paste it into another text editor then save it as a back up. This will enable to you quickly revert back to these rules if you need to.

Based upon the above example, we need to add two rules to remove both extension 2000 and extension 3000 from the collected data before the parser sees them. The rules that are needed for our example are:

tran dst_number |2000|
tran dst_number |3000|

These new rules will force the parser to explicitly translate these two numbers to null values, essentially removing them from the data before the rest of the rules are run.

Once these rules have been added, click the ‘Apply Changes’ button to save them.

In addition to using the web GUI, the CPID rules can be edited by exporting the PBX IP gateways configuration database (config.ini), making the changes in that file using a text editor, and then importing the file back in.

The CPID parsing rules are located in a block of text all the way at the end of the config.ini file.