Sipnetic is a free VoIP softphone based on the SIP protocol. It allows you to connect to your VoIP provider, cloud PBX, or an enterprise telephony server. Key features: Compatibility with all standards-compliant VoIP providers and PBXes. Supports calling over 3G and Wi-Fi. Modern UI. Great audio quality provided by the Wideband Opus codec. Legacy codecs, such as G.711, Speex, and GSM, are also supported. Acoustic echo cancellation and automatic gain control. Video calls using H.264 codec. Support for various NAT traversal techniques, including STUN, TURN, and ICE. Instant Messaging with text and voice chat capabilities. Secure calls based on TLS, SRTP, and ZRTP protocols. End-to-end encryption of chat messages with OTRv3 protocol. Integration with system contacts including built-in contact editor. Presence information support based on the SIMPLE protocol suite. Multiple SIP accounts support with automatic account selection. Classic telephony features, such as multiple waiting calls, placing call on hold, sending DTMF digits. Call transfers are expected in future releases. Experimental Walkie-Talkie mode well suited for low-bandwidth links.