SipLine
Free, native Windows SIP softphone with HD audio, SRTP encryption
SipLine is a modern, lightweight SIP softphone for Windows 10/11 built with .NET 9 WPF. It provides enterprise-grade VoIP communication with a focus on performance, security, and extensibility.
Features
Ultra-Fast: Startup in <0.5s, minimal CPU usage
HD Audio: Opus and G.711 codecs with adaptive jitter buffer
Security: TLS transport, SDES-SRTP encryption, Windows DPAPI credential protection Multi-Account: Up to 5 simultaneous SIP accounts
Plugin SDK: C# SDK for custom integrations...