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

Trying to write code for creating conference call for softphone using TAPI3.0 Here is the code Which I wrote but code is not working.

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

         开发者_如何学运维   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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basicaly TAPI is using H323 protocol and softphone use SIP which is text based protcol si the connection will not establish