During my searching for the VOIP solution i found Vopsipsdk.com which offering many Freature that include:
* Registrar support
* Dynamically loadable codecs
* SIP Proxy authentication
* Multi-party voice conference
* Play wav files into conversation
* Record conversation into file
* Hold/Retrieve call
* Forward Call (Blind Call Transfer)
* Transfer Call (Attended Transfer)
* Mute Sound
* Authorization Id
* Noise reduction
* Auto gain
And many more
Here's Softphone ScreenShot