Bartek Kania wrote:
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> On Mon, 12 Jun 2006, Max CtRiX wrote:
>> It works because the ATA sends a reinvite with T38 headers both when
>> receiving and sending a fax, so openpbx can switch to udptl.
>> But there is still a problem.
>> Openpbx in chan_sip.c actually uses dsp to try to detect fax tones and
>> send a reinvite.
>> It simply does not work. It detects nothing even if it should do it.
>
> I ran into that problem myself.
> It seems there is something wrong with the fax-tone detection.
I did the following at chan_sip about line 3180:
f = opbx_dsp_process(p->owner, p->vad, f);
if (f->frametype == OPBX_FRAME_DTMF) {
//if ((opbx_test_flag(p, SIP_DTMF) == SIP_DTMF_INBAND) && p->vad) {
if (t38udptlsupport && f->subclass == 'f') {
// Fax tone
opbx_log(LOG_DEBUG, "Fax CNG detected on %s\n", ast->name);
*faxdetect = 1;
}
// opbx_log(LOG_DEBUG, "* Detected inband DTMF '%c'\n", f->subclass);
//}
}
AND at about line 2915:
if (opbx_test_flag(i, SIP_DTMF) == SIP_DTMF_INBAND) {
i->vad = opbx_dsp_new();
#if T38_SUPPORT
opbx_dsp_set_features(i->vad, DSP_FEATURE_DTMF_DETECT |
DSP_FEATURE_FAX_DETECT | DSP_DIGITMODE_RELAXDTMF);
#else
opbx_dsp_set_features(i->vad, DSP_FEATURE_DTMF_DETECT |
DSP_DIGITMODE_RELAXDTMF);
#endif
opbx_dsp_set_threshold(i->vad, 256); ^
opbx_dsp_digitmode(i->vad, DSP_DIGITMODE_DTMF);^
if (relaxdtmf)
opbx_dsp_digitmode(i->vad, DSP_DIGITMODE_DTMF |
DSP_DIGITMODE_RELAXDTMF);
(added some dsp_settings and enabled relaxed dtmf mode)
----------------
Now: what happens ??
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: Got RTP packet from
83.211.2.133:18206 (type 0, seq 59650, ts 102256520, len 160)
Jun 12 10:22:55 DEBUG[3054783408] chan_sip.c: Fax CNG detected on
SIP/0240706874-08e0
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: set_destination: Parsing
<sip:195.62.225.244;ftag=5E929840-108D;lr=on> for address/port to sen
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: set_destination: set
destination to 195.62.225.244, port 5060
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: T.38 UDPTL is at port
88.149.167.222:8728
Jun 12 10:22:55 DEBUG[3054783408] chan_sip.c: Our T38 capability (3872),
peer T38 capability (0), joint capability (3872)
Jun 12 10:22:55 DEBUG[3054783408] chan_sip.c: T38MaxFaxRate 9600 found
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: 14 headers, 15 lines
Jun 12 10:22:55 VERBOSE[3054783408] logger.c: Reliably Transmitting
(NAT) to 195.62.225.244:5060:
and then sends a reinvite...
openpbx says:
m=image 8728 udptl t38^
cisco says:
m=image 18206 udptl t38^
-------------
the problem is that:
Jun 12 10:23:09 WARNING[3054783408] rtp.c: RTP Read too short
Jun 12 10:23:10 WARNING[3054783408] rtp.c: RTP Read too short
Jun 12 10:23:13 WARNING[3054783408] rtp.c: RTP Read too short
Jun 12 10:23:13 WARNING[3054783408] rtp.c: RTP Read too short
Cisco sends UDPTL packets on RTP port, ignoring m=image informations.
I have seen that some ATA send a SIP INFO message together with t38
udptl headers so, maybe, openpbx should do the same, maybe not
triggering this error from cisco (i have seen many dumps .
Anyway, receiving a fax from a cisco sometimes works.
Sending a fax NEVER works because openpbx NEVER sends out t38 headers.
There are no DSP functions hanged on chan_write which should trigger T38
headers upon fax detection.
I have no enought experience on this. I can hack, comment out, make
tests, but I really do not know openpbx internals.
Max
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