TC>check "H225_Setup_UUIE & H323SignalPDU::BuildSetup" within src/h323pdu.cxx
TC>(H323plus)

i think it can be implemented later, but, why it may be needed? can you explain some
situation where it need?

TC>
TC>you should handle this and postpone pre_answer until you get an open LC.

pre_answer is not complete at this time, i say it a some kinde of hack, there is
another issues with it ans sofia in case proxy-media true.

bool FSH323Connection::OnReceivedProgress(const H323SignalPDU &pdu)
{
        PTRACE(4, "mod_h323\t======>FSH323Connection::OnReceivedProgress");
        m_txAudioOpened.Wait();
        switch_channel_mark_pre_answered(m_fsChannel);
        return true;
}

so for me the workaround for this was:

bool FSH323Connection::OnReceivedProgress(const H323SignalPDU &pdu)
{
        PTRACE(4, "mod_h323\t======>FSH323Connection::OnReceivedProgress");

        PTRACE(4, "mod_h323\t======>FSH323Connection::OnReceivedProgress - disabled pre_answer!!!!");

        //m_txAudioOpened.Wait();
        //switch_channel_mark_pre_answered(m_fsChannel);
        return true;
}