[Freeswitch-users] start_dtmf when no RFC 2833

Hi All, The following dial plan detects RFC 2833 and if it is not present, runs the "start_dtmf" application. <condition field="${switch_r_sdp}" expression="a=rtpmap:(\d+)\stelephone-event/8000" break="never"> <action application="set" data="rtp_payload_number=$1"/> <anti-action application="start_dtmf"/> </condition> I need to do this on the outbound leg - using Lua. Can anyone point me to some code example that would achieve this or get me started? Any help appreciated. Thanks Phil