How to communicate on different networks using iConf.net ?

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C#

i am using iconf.net for video and Audio chat but it works on same network and not working on different networks. i think to communicate on different networks "Public Ip reqiured " but its not working with public IP ,i got my public ip on http://www.whatismypublicip.com. Is it a good way to get Public IP ?
how can i communicate on different networks and how can i get my public IP?

What I have tried:

I tired with Private

icc.Call(ipToCall, videoPort, 0, 0, "test", ics.CallBackId, myIp, videoPort, audioTcpPort, audioUdpPort, "")

but Not Working with public IP