Aqorin Phone is an open-source, cross-platform SIP softphone built with .NET that enables users to make and receive calls using standard SIP credentials without requiring proprietary accounts or ecosystems. The application offers essential calling features including muting, holding, contact management, and call history, with support for both manual SIP configuration and router profiles. It uses standard SIP signaling and RTP audio, making it compatible with PBX systems and router-hosted phone accounts.