if anybody used it.. let me know its performance

Leo-

Judging by the way you phrased your post, I suspect you are a salesman for
Dingotel!

Therefore, you probably don't want to hear that a two-way radio version of VOIP
can be implemented without any such product. It is commonly done using
software called "EchoLink", with your computer's built-in sound capability.

Check out http://www.echolink.org/. Software can be downloaded for free, and
is available for both Windows and Macintosh computers, and probably others.

73, Fred, K4DII