Ozeki VoIP SIP .NET SDK provides VAD support for detecting incoming voice activity of phone calls. The sample program can be used as a silence filter during VoIP calls. It is mainly used by predictive dialer systems to differentiate human & machine. Ozeki .NET SDK allows to further improve this sample with features like handling multiple lines & calls, DTMF signals, .wav or .mp3 file recording & playing, SIP voice/video calls, developing own softphone, Silverlight/Flash text/voice/video chat programs, supports web-to-web voice and video calls, etc. It is based on the extraordinary background support Ozeki VoIP SIP SDK provides. The sample demonstrates how to use the VADFilter class. It is used for detecting the incoming voice activation form a phone call meaning that the detecting algorithm is capable of specifying when the remote party speaks and it differentiates it from the silence periods. Voice Activation Detection is mainly used in predictive dialer systems, when you need to specify if the remote party is a human or an answering machine. Due to the flexibility of Ozeki VoIP SIP SDK improvements are available for this sample (like jitter buffer, Voice Activity Detection, Acoustic Echo Cancellation, Packet Lost Concealment (PLC), Call timer, Customized with Company Logo/Name, Unlimited User License, Full HD video, Multiple lines for multiple concurrent calls, Conferencing, Call history, Quick calling and re-dialing, etc.). It ensures compatibility with almost all PBX systems like Asterisk PBX, Cisco UCM, 3CX Phone System, Kamailio PBX, etc. Ozeki SDK also works with almost all VoIP service providers (Skype Connect, Gafachi, Callcentric, SureVoIP, VoIPtalk, etc.) due to that it is fully standard compliant. After an Ozeki VoIP SIP SDK .Net license has been purchased you can feely use the license with your product and may freely distribute your product in as many copies as you want, and for as long as you wish without any royalties or license fees paid for Ozeki.