Hi, I have implemented the solution for tone detection in wiki, and also answer the channel before detecting the tone: <condition field="destination_number" expression="^(055138419992)$"> <action application="answer"/> <action application="tone_detect" data="fax 1100 r +15000 transfer fax XML default"/> <extension name="fax"> <condition field="destination_number" expression="^fax$"> <action application="answer" /> <action application="sleep" data="1000"/> <action application="rxfax" data="/usr/local/freeswitch/storage/fax/${caller_id_number}-${strftime(%Y-%m-%d-%H-%M-%S)}.tiff"/> <action application="set" data="fax_mode=recv"/> <action application="hangup"/> </condition> </extension> But FS cannot recognize the tone, and therefore cannot move to fax extension. Below are the error in FS: 2009-10-12 10:57:16.702287 [NOTICE] switch_channel.c:602 New Channel sofia/external/anonymous@anonymous.invalid [c431f0a3-9231-4724-ba39-9e4ef7edfca2] 2009-10-12 10:57:16.703413 [INFO] mod_dialplan_xml.c:315 Processing Anonymous->055138419992 in context public 2009-10-12 10:57:16.719288 [NOTICE] switch_ivr.c:1349 Transfer sofia/external/anonymous@anonymous.invalid to XML[055138419992@default] 2009-10-12 10:57:16.719288 [INFO] mod_dialplan_xml.c:315 Processing Anonymous->055138419992 in context default 2009-10-12 10:57:16.722289 [NOTICE] mod_dptools.c:649 Channel [sofia/external/anonymous@anonymous.invalid] has been answered 2009-10-12 10:57:16.722289 [NOTICE] mod_dptools.c:1324 Enabling tone detection 'fax' '1100' 2009-10-12 10:57:16.723302 [NOTICE] switch_core_state_machine.c:179 Hangup sofia/external/anonymous@anonymous.invalid [CS_EXECUTE] [NORMAL_CLEARING] 2009-10-12 10:57:16.740285 [NOTICE] switch_core_session.c:1086 Session 1 (sofia/external/anonymous@anonymous.invalid) Ended 2009-10-12 10:57:16.740285 [NOTICE] switch_core_session.c:1088 Close Channel sofia/external/anonymous@anonymous.invalid [CS_DESTROY] And the trace for SIP messages: http://pastebin.com/m4e47e7d9 If anyone has any idea, tell me please. Thanks. -- View this message in context: http://n2.nabble.com/Question-about-fax-tone-detection-tp3807298p3807298.htm... Sent from the freeswitch-users mailing list archive at Nabble.com.