There are several potential issues that can prevent voice applications from loading. The most common problem is when a voice application is deployed from Studio but its "deployApp" administrative script is not run on Call Services. In that case, the application's data files are present on Call Services, but it is not yet actively accepting callers.
Another common problem is incorrect general settings for the application. "Deploy version" and "Gateway adapter" should have appropriate values for the particular environment.
Prior to calling into the application, status of the application should be checked using the administrative script status.bat or status.sh, depending on the OS used. This local status script will output status for this particular application, while the global static script (in AUDIUM_HOME/admin) will list all the applications currently deployed on the Call Services instance.
Please refer to the following articles for full descriptions of the above problems and proposed solutions: