April 2026: Delivered a critical bug fix to SIP Contact URI port/transport formatting for contact_mode=0 in kamailio/kamailio, restoring correct URI generation and preventing misrouted SIP contacts. The change preserves 6.0 behavior while aligning with 6.1 refactors, maintaining backward compatibility and stability. Implemented targeted TPS contact-building adjustment to pass append_port_proto=1 for TPS_CONTACT_MODE_SKEYUSER, ensuring port and transport are preserved in generated contacts. Documented the fix with a co-authored commit and kept changes focused and well-scoped. Overall impact: improved call routing accuracy, interoperability, and production reliability; technical achievements include precise URI handling, code refactoring alignment, and robust documentation.