This error occurs because the SDK jar file is not added to the application. Steps to fix this issue:

1. Go to the properties of the application.
2. Select Java BuildPath.
3. In Libraries Tab, Press "Add Jar" button and add the SDK_NAME.jar file.
4. Now go to "Order and Export" tab and Check/Select the "SDK_NAME.jar" file and press OK.
5. Rerun the application now.

Yes, please do. AT&T provides these SDKs to make the development of applications using APIs provided by AT&T as fast and simple for you as possible.

Yes, to run the SDK Sample Apps you must first create a new app in My Apps to acquire an App Key and App Secret.

The short code is optional. It is only needed by SDKs that require AT&T Wireless customer consent to allow the apps to use the customer’s AT&T Wireless mobile number.