Fully featured SIP client. Kapanga Softphone is a powerful and unique SIP software telephone that lets users make phone and video calls as well as send/receive fax from one single software application using any Voice over IP (VoIP) telephony provider.

Kapanga Softphone is:
1. a new way of thinking about SIP clients
2. designed from the ground up for reliability and flexibility
3. adaptive to current and future IP-based communications systems

As a fully featured SIP client, Kapanga Softphone is designed from the ground up to work with current and future IP-based communications systems and infrastructure. Kapanga Softphone has also been tested by our engineers and softphone users across many VoIP hardware, IP-based PBX software and service providers in North America, Europe, Asia and Latin America.

Kapanga Softphone Features:
SIP related:
1. RFC 3261 Call Control Compliant
2. Custom incoming call ring tones using MIDI files
3. ALERT-INFO header management
4. DTMF generation/detection (Inband and RFC 2833)
5. Real time Mean Opinion Score (MOS) Estimation
6. SIP Registration
7. Full STUN/NAT support
8. Secure SIP sockets over TCP/TLS
9. Jabber / XMPP Instant Messaging and Presence

Voice:
1. Real time Quality Monitoring (MOS)
2. 3 independent phone lines
3. Auto-Answer/Do Not Disturb
4. Call Forwarding
5. Full Duplex Audio Recording

Fax:
1. Fully ITU Group 3 Compliant
2. Fax machine detection and CNG generation
3. Standard and High Resolution
4. V.17, V.27, V.29 support
5. Customizable Header Text

Video:
1. Picture in Picture Video (simultaneous local and remote video)
2. On-Screen Audio/Video Bandwidth
3. Full Duplex Video Recording

Supported Codecs:
1. Voice: G.711 (A and m-law), G.722.1, G.723.1, G.726, G.728, G.729A/B/D/E, AMR, GSM 6.10/EFR, iLBC, Speex
2. Video: H.263/RFC 2190, H.263/RFC 2429, H.264/RFC 3984, MPEG-1, MPEG-2, Theora
3. Fax: T.38 (MH, MR, MMR and ECM)
(please note that some codecs listed here are only available to OEMs)

Kapanga Softphone is the premier Session Initiation Protocol (SIP) based client capable of voice, video and fax over IP communications using any Internet Telephony Service Provider (ITSP), VoIP-enabled Enterprise or Software IP-PBX.

The license of this software is Freeware, you can free download and free use this internet phone software.