When we download the entire SDK, there is one .jar file which is for stub testing and a .aar file named msdc_api-MSDC_LA_4.2.01.04.0.aar. When i add .jar as a library I am able to get the appropriate callbacks for groupcall service(like groupCallServiceStarted) even if MSDC middleware is not installed on the device. However when i use .aar file , even if the middleware is installed on the device , groupcall service state is returning null (using the api mGroupCallModel.getGroupCallServiceState). Can you please mention the basic difference between this stub .jar file and msdc_api .aar file? How come appropriate call backs for groupcall service comes even if middleware is not installed in case of stub .jar? If i use .aar file , will the callbacks for groupcallservice work only if proper LTE Network and Middleware is setup?