Worked on the kamailio/kamailio repository to deliver support for Custom Call ID and From Tag handling in SIP req_outside processing. Focused on enhancing SIP session traceability and interoperability, the implementation reused client-provided identifiers when available and generated new ones only as needed, reducing unnecessary ID creation and potential mismatches. This approach improved observability and compatibility with external SIP endpoints by preserving identifiers across requests. The work centered on core SIP protocol handling and network programming, utilizing C to ensure reliability and performance. The feature addressed business needs for personalized, trackable SIP sessions while aligning with established reliability and efficiency goals.