We are encountering an issue with PJSIP in our Android application. When the app is in a killed state and receives an FCM event related to a call, we initiate the PJSIP library initialization followed by the SIP registration process. However, we are consistently receiving a 503 response most of the time, even though the server is Up and Running with TLS configuration. But its fine with TCP. Here REGISTER request is not reaching the server anymore