Modify an Android Application - Integrate default Android SIP call interface (incoming / outgoing / during call) into an existing SIP voice calling application

Please note: This project is to modify an existing / working SIP voice calling Android application. It is not to create a new application from scratch. You will be required to modify existing code without introducing errors or any conflicting issues with the current app. Project Requirement: You will be provided with an SIP application which has a custom app interface for incoming SIP calls, outgoing SIP calls, and 'during-call' SIP interface during an SIP call. Your task is to change these to use the default Android interface for incoming calls, outgoing calls and 'during-call', according to official Android guidelines such as: [login to view URL] After your modifications, the app should be able to correctly handle incoming / outgoing SIP calls through the default Android interface used for SIP calls in the latest versions of Android. It must work with the SIP profiles set in the app settings. If you have any questions, please ask.