how to write c# code for creating a conference call for softphone using TAPI3.0

Question

I had developed some code

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private void button7_Click(object sender, EventArgs e) { IEnumCall ec = ia[line].EnumerateCalls(); uint arg = 0; ITCallInfo ici;

        try
        {
            ITBasicCallControl  bc1 = ln.CreateCall(textBox1.Text, TapiConstants.LINEADDRESSTYPE_IPADDRESS, TapiConstants.TAPIMEDIATYPE_AUDIO);
            ec.Next(1, out ici, ref arg);
            ITBasicCallControl bc = (ITBasicCallControl)ici;
            bool fysync=true ;
            bc.Conference(bc1, fysync);
            ITCallHub ch = ici.CallHub(ch);
            //ITCallHub ch = (ITCallHub)ici;

ici.ReleaseUserUserInfo();

        }
        catch (Exception exp)
        {
            MessageBox.Show("No call to conference!", "TAPI3");
        }
    }

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which is not working

Answer 1

basicaly TAPI is using H323 protocol and softphone use SIP which is text based protcol si the connection will not establish