<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Hello,</div><div class=""><br class=""></div><div class="">I want to send a fax between two freeswitches (1.4.20) via T.38. On the SENDER freeswitch, I have Sangoma A104 TDM card and use the following dialplan: </div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="export" data="fax_enable_t38=true"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="color: rgb(41, 249, 20);" class=""> </span><span style="color: rgb(52, 187, 199);" class=""><action</span><span style="color: rgb(52, 189, 38);" class=""> application="export" data="fax_enable_t38_request=true"/</span><span style="color: rgb(52, 187, 199);" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="export" data="fax_verbose=true"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="export" data="execute_on_answer=t38_gateway self"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="color: rgb(41, 249, 20);" class=""> </span><span style="color: rgb(52, 187, 199);" class=""><action</span><span style="color: rgb(52, 189, 38);" class=""> application="bridge" data="sofia/external/${destination_number}@${destination_ip}"/</span><span style="color: rgb(52, 187, 199);" class="">></span></div></div><div class=""><br class=""></div><div class="">On the RECEIVER freeswitch I use the this dialplan:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""> <action</span> application="answer" /<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="playback" data="silence_stream://2000"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="set" data="fax_enable_t38_request=false"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="export" data="fax_enable_t38=true"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #29f914" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class=""><action</span> application="rxfax" data="/tmp/FAX-${uuid}.tiff"/<span style="font-variant-ligatures: no-common-ligatures; color: #34bbc7" class="">></span></div></div><div class=""><br class=""></div><div class="">When I try to send a fax, on the RECEIVER freeswitch, I can see in the (second) INVITE the T.38 data is present: </div><div class=""><br class=""></div><div class="">...</div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxVersion:0</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38MaxBitRate:14400</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxFillBitRemoval</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxRateManagement:transferredTCF</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxMaxBuffer:2000</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxMaxDatagram:400</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""> a=T38FaxUdpEC:t38UDPRedundancy</div></div><div class="">…</div><div class=""><br class=""></div><div class="">On the SENDER side I can see that it tries to start the t38_gateway</div><div class=""><br class=""></div><div class="">…</div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.092799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 2: IFP 00</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.092799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 2: indicator no-signal</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.092799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Changing - (0) ced -> no-signal</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.092799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Changing to no-signal</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.092799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Non-ECM mode</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 3: IFP 06</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 3: indicator v21-preamble</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Changing - (0) no-signal -> v21-preamble</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Changing to v21-preamble</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:51.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G Non-ECM mode</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:52.072799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38G HDLC underflow at 4</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:52.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 4: IFP c0 01 80 00 00 ff</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:36:52.172799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Rx 4: (0) data v21/hdlc-data + 1 byte(s)</div></div><div class="">…</div><div class=""><br class=""></div><div class="">But then fails with a protocol error</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:34:07.652799 [DEBUG] mod_spandsp_fax.c:286 FLOW T.38 Tx 1: indicator v21-preamble</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(195, 55, 32); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:34:07.652799 [ERR] mod_spandsp_fax.c:659 INVALID WRITE: 8:3</div><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(175, 173, 36); background-color: rgb(0, 0, 0);" class=""><span style="color: rgb(195, 55, 32);" class="">2015-09-17 23:34:07.652799 [ERR] mod_spandsp_fax.c:671 TERMINATING T30 STATE</span></div></div><div class="">…</div><div class=""><div style="margin: 0px; font-size: 14px; font-family: Menlo; color: rgb(213, 59, 211); background-color: rgb(0, 0, 0);" class="">2015-09-17 23:34:07.652799 [WARNING] mod_spandsp_fax.c:286 PROTOCOL_WARNING T.38 Tx packet handler failure</div></div><div class=""><br class=""></div><div class="">On the RECEIVER side the fax fails with „result (49) The call dropped prematurely“. Can this be because of a wrong configuration (dialplans/mod_spandsp), or is this a bug?</div><div class=""><br class=""></div><div class="">Thanks and Regards</div><div class=""><br class=""></div><div class="">Markus </div><div class=""><br class=""></div></body></html>