void SIPTransaction::sendResponse(
  const SIPMessage::Ptr& pResponse,
  const OSS::IPAddress& sendAddress)
{
  if (!pResponse->isResponse())
    throw OSS::SIP::SIPException("Sending a REQUEST using sendResponse() is illegal!");

  SIPTransaction::Ptr pParent = getParent();

  if (!_transport && isParent())
    throw OSS::SIP::SIPException("Transport Not Ready!");
  else if (!isParent() && pParent)
    _transport = pParent->_transport;

  if (_sendAddress.getPort() == 0)
    _sendAddress = sendAddress;

  SIPTransaction::Ptr pBranch = findBranch(pResponse);

  if (pBranch)
  {
    pBranch->sendResponse(pResponse, sendAddress);
    return;
  }
  else
  {
    //
    // No branch is found.  This instance will handle the response
    //
    if (_transport && _transport->isReliableTransport())
    {
      if (_transport->writeKeepAlive())
      {
        writeMessage(pResponse);
      }
      else
      {
        //
        // Keep-alive failed so create a new transport
        //
        if (_localAddress.isValid() && _sendAddress.isValid())
        {
          //
          // According to RFC 3261, if there is any transport failure, we must try to
          // re-estabish a connectoin to the via sentby parameter instead
          //
          std::string transport;
          if (SIPVia::msgGetTopViaTransport(pResponse.get(), transport))
          {
            _transport = _transportService->createClientTransport(_localAddress, _sendAddress, transport);
            writeMessage(pResponse);
          }
        }
        else
        {
          OSS_LOG_ERROR("SIPTransaction::sendResponse - Unable to re-establish transport to send response.");
        }

      }
    }
    else if (_transport)
    {
      //
      // This is UDP so a keep-alive check won't do us any good
      //
      writeMessage(pResponse, _sendAddress);
    }
    else
    {
      OSS_LOG_ERROR("SIPTransaction::sendResponse - Transport is NULL.");
    }
  }
}