[Freeswitch-users] T.38/spandsp_fax interop problem
Marcin Gozdalik
gozdal at gmail.com
Wed May 16 20:45:44 MSD 2012
Hi
I'm trying to send fax from FreeSWITCH to PSTN using T.38. FS is connected
to Broadsoft softswitch. The softswitch is connected to PSTN using
SIP-trunk to external provider. Apparently there is no T.38 on Broadsoft
and it is provided by the external provider (i.e. Broadsoft provides only
T.38 pass-through).
I can receive faxes destined at FS without a problem. I call rxfax and FS
sends re-INVITE to Broadsoft and T.38 transmission begins.
However, when I want to send fax, I can't get re-INVITE from Broadsoft with
T.38. From the company that operates the Broadsoft softswitch I received a
PCAP of working transmission with Linksys/SPA2102-5.2.10: SPA2102 issues
re-INVITE itself when sending fax and T.38 is negotiated correctly.
Unfortunately I can't get FS to issue the re-INVITE.
I thought that a part of the problem is that FS receives from Broadsoft
RTP-event Fax ANS (32) messages and it somehow interferes with
fax-detecting routing in spandsp. Unfortunately, disabling telephone-event
altogether didn't help - Broadsoft does not sent RTP-event packets but
still FS does not re-INVITE.
My sending script is as follows:
var variables = "{";
variables += "loopback_bowout=false,";
variables += "ignore_early_media=true,";
variables += "origination_caller_id_number='" + callerid + "',";
variables += "origination_caller_id_name='" + callername + "',";
variables += "fax_ident='" + callerid + "',";
variables += "fax_header='" + callername + "',";
variables += "fax_email='" + email + "',";
variables += "fax_dest='" + dest + "',";
variables += "fax_tiff='" + tiff + "',";
variables += "fax_attempt='" + attempt + "',";
variables += "fax_max_attempts='" + max_attempts + "',";
variables += "fax_delay='" + delay + "',";
variables += "fax_enable_t38=true,";
variables += "fax_enable_t38_insist=true,";
variables += "fax_enable_t38_request=true,";
variables += "fax_disable_v17=false,";
variables += "fax_use_ecm=true,";
//variables += "fax_force_caller=true,";
variables += "fax_verbose=true";
variables += "}";
var s = new Session(variables + "loopback/"+dest+"/pbx/XML");
hook_run = 0;
s.setHangupHook(hangup_hook);
if (s.ready()) {
console_log("DEBUG", "calling txfax\n");
s.execute("txfax", tiff);
console_log("DEBUG", "returning from txfax" + "\n");
} else {
console_log("INFO", "sending fax from " + callerid + " to " + dest
+ ": could not connect: " + s.cause + "(" + s.causecode + ")" + "\n");
return;
}
I do send the fax through loopback as I need it to establish rating
session. I have experimented with various settings in fax_* variables. The
only combination where anything happens (there is some T.30 negotiation in
the logs) is when I set fax_enable_t38_request to false - then FS tries to
negotiate T.30 transmission over G.711. I've never observed T.38 connection
when sending fax, but it always ends with (20) Received no response to DCS
or TCF.
Usually the only thing there is in the logs is:
2012-05-16 17:27:19.824842 [DEBUG] mod_spandsp_fax.c:1357 Raw read codec
activation Success L16 20000
2012-05-16 17:27:19.824842 [DEBUG] mod_spandsp_fax.c:1373 Raw write codec
activation Success L16
2012-05-16 17:27:22.124834 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:22.884832 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:23.444834 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:23.784833 [DEBUG] switch_rtp.c:3452 RTP RECV DTMF
2012-05-16 17:27:23.804833 [DEBUG] switch_rtp.c:3452 RTP RECV DTMF
2012-05-16 17:27:26.544834 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC sig
nal status is Carrier down (-1) in state 18
2012-05-16 17:27:26.544834 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:27.264833 [DEBUG] switch_rtp.c:3452 RTP RECV DTMF
2012-05-16 17:27:27.284873 [DEBUG] switch_rtp.c:3452 RTP RECV DTMF
2012-05-16 17:27:27.604841 [DEBUG] switch_rtp.c:3452 RTP RECV DTMF 2012-05-
16 17:27:28.884836 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC signal
status is Abort (-8) in state 18
2012-05-16 17:27:28.884836 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:30.704933 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:30.764833 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:31.904833 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:34.544835 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:37.544837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:40.164835 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:41.184835 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:41.224837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Abort (-8) in state 18
2012-05-16 17:27:41.224837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:43.184834 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:44.824838 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:45.664833 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:45.664833 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:45.724837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:45.724837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:45.784837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier up (-2) in state 18
2012-05-16 17:27:45.804837 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 HDLC
signal status is Carrier down (-1) in state 18
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 Status
changing to 'The call dropped prematurely'
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:491
==============================================================================
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:504 Fax processing not
successful - result (49) The call dropped prematurely.
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:509 Remote station id:
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:510 Local station id:
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:511 Pages transferred:
0
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:513 Total fax pages:
0
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:514 Image resolution:
0x0
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:515 Transfer Rate:
14400
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:517 ECM status
off
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:518 remote country:
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:519 remote vendor:
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:520 remote model:
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:522
==============================================================================
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 Changing
from state 18 to 32
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW T.30 Changing
from phase T30_PHASE_A_CNG to T30_PHASE_CALL_FINISHED
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW FAX Set rx
type 9
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW FAX FAX
exchange complete
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW FAX Set tx
type 9
2012-05-16 17:27:46.304847 [DEBUG] mod_spandsp_fax.c:286 FLOW FAX FAX
exchange complete
The same script transmits faxes correctly with Cisco gateway, but Cisco
correctly re-INVITEs FS when FS is transmitting fax.
PCAP dumps available, but I'd like to keep them private and not post on
public pastebin.
I'd appreciate any help on this issue.
Best regards
--
Marcin Gozdalik
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