[Freeswitch-users] spandsp_start_fax_detect sometimes miss fax detection

Hello, I am using the above application to detect an incoming fax. My dialplan has the following code: <action application="set" data="execute_on_answer=spandsp_start_fax_detect transfer 'fax_${dest}' XML ${context}' 10 cng"/> When using the same fax machine to send, sometimes it detects the fax, sometimes not. This mainly happens when the call lands into voicemail; when answering the call the success rate is much higher (almost 100%). Is there any way to "tune" this detection? Or shall I use something different than "execute_on_answer" for voicemail? Thanks! __Yehavi: