Tapiex call coferance

I am using TAPIEX to devolve a IVR system. I want to devolve a conferrence system in this case,. But I am getting error:
 
Line:'Nokia 7230 USB Modem (HCALL:0x10267)' SetupTransfer() method failed, TAPI Error Code=ERR_OPERATIONUNAVAIL
Line:'Nokia 7230 USB Modem' Warning: method 'SetupTransfer()' is not supported in the device.

Private Sub BnTransferDial_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles BnTransferDial.Click
 
        'mCall will be in onHoldPendingTransfer state , ConsultCall will in dialtone
        If mCall.SetupTransfer() Then
            Sleep(1000)
            bnSwapHold.Enabled = True
            BnTransferComplete.Enabled = True
            BnThreeWay.Enabled = True
            'use ITAPILine.ConsultCall to obtain the consultation call.
            mCall.LineOwner.ConsultCall.Dial(TextTransferPhoneNumber.Text)
        End If
 
    End Sub

I dont't know why this is happennig? suggest something