Ozeki VoIP SIP .Net SDK allows to develop C# VoIP softphone to make/receive voice and video calls. The program supports basic telephony functions like register to a SIP PBX, make a Voice Call, handle audio peripherals in softphone, playing voice from the microphone, playing mp3 file, text to speech, playing incoming voice, incoming voice recognition, accept an incoming call, reject an incoming call, forward an incoming call, blind Transfer, attended call transfer, hold a call, use DTMF signaling, working with SDP in VoIP SIP calls, working with RTP in VoIP SIP calls, Auto Answer, Do not Disturb (DND), make a Video Call, HD video, Video devices, Video codec support. EXTENDED CODEC SUPPORT: Ozeki VoIP SIP SDK has been developed to ensure excellent sound quality. For this purpose various codecs are supported: G.711 aLaw/uLaw, G.729(b), iLBC, GSM, G.722, SPEEX, SPEEX-WB. With the help of its advanced network handling, it will work behind NAT. Fully compatible with your SIP infrastructure. CUSTOMIZABLE FEATURES AND GUI: You can easily customize the features and GUI of your softphone when you use Ozeki VoIP SIP SDK. ON-LINE VOIP SERVICE SUPPORT: Ozeki SIP SDK works with almost all VoIP service providers (Skype Connect, Gafachi, Callcentric, SureVoIP, VoIPtalk, etc.) due to that it is fully standard compliant. OUTSTANDING PBX COMPATIBILITY: Ozeki SIP SDK is compatible with the most of PBXs such as Cisco UCM, Asterisk PBX, 3CX Phone System, Kamailio, OpenSIPS, SipX ECS, Elastix, etc. Due to the flexibility of Ozeki SIP SDK, the developed softphone can be further improved with additional features like: Jitter buffer, Voice Activity Detection, Acoustic Echo Cancellation, Packet Lost Concealment (PLC), Call timer, Customized with Company Logo/Name, Unlimited User Licence, Full HD video, Multiple lines for multiple concurrent calls, Conferencing, PC-PC or PC-phone calls, Caller ID with name, Quick calling and re-dialing, Call history, Connect to PSTN and mobile phones