Activating T38 passtrough in FreePBX

Hi!

I am using Trixbox 2.6 , Asterisk 1.4 with FreePBX 2.4.
My setup includes a SIP telephony provider (wich use T38 for faxing), and lots of ATAs (T38 activated)
Now, I want to activate the T38 passtrough to be able to fax.
T38-SIP-provider <====> Asterisk <====> T38-ATA

However, it does not seems to work “out of the box”, and I do not know of any options to set the passtrough behaviour.
I have seen some info there and there, but nothung clear, and some howtos included messing into sip_additional.conf SIP extension’s config, a thing FreePBX wans not to do.

Have I missed something?
How can one activate the asterisk 1.4 + T38 fax passtrough ?

Thanks!

For T.38 you need to…

  1. Setup /etc/asterisk/udptl.conf manually
  2. add “t38pt_udptl=yes” to /etc/asterisk/sip_general_custom.conf

#2 basically tells asterisk that ALL of your SIP peers are T.38 capable (which is probably not true, but not really harmful either)

Unfortunatly I do not believe there is a “good” way using freepbx to add t38pt_udptl=yes to individual SIP peers…

This should probably be added to freepbx though… but its also perfectly possible its already been done as a patch and is in Trac already.

mwatson,
there is no harm in doing what you said so at this point there are no immediate plans to add it to the device level.

I don’t know what ATA you are using, but just to pass on my experience:

I tried using Linksys spa2102 since that states it can handle T.38
I connected up a fax machine to it, and tried to send a fax, via a VOIP provider that says they have many people faxing out using their service.
I could not get the spa2102 to work to do this with T.38, but it works 96% using G.711
(I am going directly from ATA out to VOIP provider, not through Asterisk).
And I have seen other posts that this subject is not exactly standardized enough to just work.
I would love to hear if you have an ATA that does work, and what the settings are.

Philippe,

Agreed, its not really harmful indicating that all of your peers are T.38 capable… the only thing I can see that might possible happen (and I’ll fully admit ahead of time that this is a ridiculas scenerio and should never happen in the real world…)

If somebody has a mix of peers that are fax-capable, but only some are T.38 capable… if a T.38 device and a non-T.38 device try and fax between each other it would fail… T.38-capable device will attempt to send a T.38 re-invite to the non-T.38-cabpe device that is falsly advertising itself as T.38-capable and I imagine the fax machines would fail to negotiate with each other… since one will be trying to do it over T.38 while the other is still trying to do it over the RTP channel… I can;t this setup in the real world though.

jperry,

I;m using Linksys SPA2102 ATA’s successfully with T.38.

I;m using the Attrafax modules available from Attractel for doing T.38 gatewaying (note: I do not work for them or endorse them in any way… just what I happen to be using).

I did have problems with the SPA2102 and attrafax at first, but updating the firmware on the ATA’s resolved the problem… might want to give that a try… I think I was running firmware 5.1.6 when I had problems… now I;m running 5.2.3, which is the latest release.

Try updating your firmware if you aren;t running 5.2.3 and see if that fixes your problem too… I can probably also help you with the settings i used on my SPA if you still have troubles.

@jperry: I was using G.711, but my fax machine cannot be configured to go below 14.4, our internet is not perfectly reliable and most of our client use matusalem-class fax machines in remote areas where land lines are bad… It worked, but with about 60% sucess… I had to get T.38 running to garantee a better sucess rate.

Ok, I just configured as told, and it works now.
I must however configure “canreinvite=no” on the fax target ATA (or else, it tries to bypass asterisk completly in the t.38 reinvite!! Must be an asterisk bug…)

My ATA is a Mediatrix 1102. I ran a Wireshark trace between the ATA and Asterisk (Trixbox 2.6), and can confirm the G.711 conversation converted to T.38 as soon as the fax tone was heard.

Tested both incoming and outgoing (With a Fax on a POTS Landline)
My SIP provider is Babytel (very friendly, and advertised as t.38 compliant) .

Thanks to all of you! It works :smiley:

mwatson, yes please give me your spa2102 settings to make T.38 faxing work. I do have firmware 5.2.3 now on the device. I am using Gafachi – they specifically advertise T.38 and I spoke with their tech-support and they say they have customers doing thousands of minutes of faxing per month using T.38. So I think it is just some settings in my device. (Very response tech-support – answers the phone right away, but they have no help for configuring the devices.)

In the spa2102, I gather most settings are on the Line-X tab, and have the word “FAX” in them. But also on the SIP tab, what is your “RTP Packet Size” (I have .020), and any other relevant setting?

Hey jperry,

here are the settings I use on my SPA

on the "Line " tab:

FAX CED DETECT ENABLE: yes
FAX CNG DETECT ENABLE: yes
FAX PASSTHRU CODEC: G711u
FAX CODEC SYMMETRIC: yes
FAX PASSTHRU METHOD: ReINVITE
FAX PROCESS NSE: yes
FAX DISABLE ECAN: no
FAX ENABLE T38: yes
FAX T38 Redundancy: 1
FAX TONE DETECT MODE: caller or calee

Other chnages that I know i did…

PREFERRED CODEC: G711u
SILENCE SUPPRESSION ENABLE: no
ECHO CANC ENABLE: no
ECHO CANC ADAPT ENABLE: no
ECHO SUPP ENABLE: no

Then on the asterisk side…

my udptl.conf contains:

udptlstart=4000
udptlend=4999
T38FaxUdpEC = t38UDPRedundancy
T38FaxMaxDatagram = 400
udptlfecentries = 1
udptlfecspan = 3

and then of course in sip.conf i have:

t38pt_udptl = yes

mwatson, thank you for your settings.
I tried that on the spa2102 and it does not seem to work for me yet
(not going thru asterisk, just direct to VOIP-provider).

I am trying to make an outgoing fax call via
spa2102-> VOIP-provider -> PSTN -> POTS fax machine.
It connects to the other fax machine, and when I listen in on another phone on the same line, I hear the obvious fax “conversation” between the two, but at the end it tries lower speeds and gives up. I get a blank piece of paper on the receiving fax machine.

Question:
During the fax call, the spa2102 “Info” tab (when I refresh during the call) shows
Call 1 Encoder: ?
Call 1 Decoder ?
Call 1 FAX: Yes
Is that what yours shows?

Thank you

jperry,
in order to use t38, your provider needs to also support receiving t38. Most don’t. You should confirm that.

I’ll second what lindheimer said… does your provider actually support T.38? like he said, most don’t… if you are in the states, I believe gafachi is a fairly popular sip provider that supports T.38.

Something else you might want to do is setup a syslog server… on your SPA2102 there is a place to specify a syslog & debug server (debug is actually syslog too… its just extra info). put your syslog server into both fields and crank the debug level up and see what the SPA is spitting out.

I’m not sure about what the SPA says on the info tab during the call… i’ll try and watch it today.

Yes, I am using Gafachi, and yes they tell me they have broadcast fax customers that use their T.38 service.
Now using the spa2102 syslog feature:

It ties to send the fax at the point of
[1]FM 00039730 Tx T38: d.v29_9600 . . .
then tries lower speeds.

— OBJ POOL STAT —
OP:RTPRXB = 96 ( 96 192) OP:RTPREB = 40 ( 40 48)
OP:RTPTXB = 64 ( 64 108) OP:TIMEOU = 110 (120 52)
OP:SIPCOR = 0 ( 1 28) OP:SIPCTS = 32 ( 32 1140)
OP:SIPSTS = 32 ( 32 6620) OP:SIPAUS = 0 ( 8 588)
OP:SIPDLG = 10 ( 10 148) OP:SIPSES = 12 ( 12 9776)
OP:SIPREG = 2 ( 4 304) OP:SIPLIN = 0 ( 2 140)
OP:SUBDLG = 2 ( 2 6436) OP:STUNTS = 16 ( 16 68)
OP:XMNODE = 1024 (1024 112)
[1]Off Hook
2. Report digit 1 (1)(40 ms)
2. Report digit 4 (1)(40 ms)
2. Report digit 0 (1)(40 ms)
2. Report digit 8 (1)(40 ms)
2. Report digit 4 (1)(40 ms)
2. Report digit 4 (1)(40 ms)
2. Report digit 5 (1)(40 ms)
2. Report digit 0 (1)(40 ms)
2. Report digit 7 (1)(40 ms)
2. Report digit 2 (1)(40 ms)
2. Report digit 2 (1)(40 ms)
Calling:[email protected]:0
[1:0]AUD ALLOC CALL (port=16396)
[1:0]RTP Rx Up
[1]->64.192.112.13:5060(1078)
[1]->64.192.112.13:5060(1078)
INVITE sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-d4cb6745

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected]

Remote-Party-ID: “Fax” sip:[my_username]@64.192.112.13;screen=yes;party=calling

Call-ID: [email protected]

CSeq: 101 INVITE

Max-Forwards: 70

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

Expires: 240

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 446

Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER

Supported: x-sipura, replaces

Content-Type: application/sdp

v=0

o=- 67094905 67094905 IN IP4 192.168.1.31

s=-

c=IN IP4 192.168.1.31

t=0 0

m=audio 16396 RTP/AVP 0 2 4 8 18 96 97 98 100 101

a=rtpmap:0 PCMU/8000

a=rtpmap:2 G726-32/8000

a=rtpmap:4 G723/8000

a=rtpmap:8 PCMA/8000

a=rtpmap:18 G729a/8000

a=rtpmap:96 G726-40/8000

a=rtpmap:97 G726-24/8000

a=rtpmap:98 G726-16/8000

a=rtpmap:100 NSE/8000

a=fmtp:100 192-193

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=ptime:20

a=sendrecv

[1]<<64.192.112.13:5060(547)
[1]<<64.192.112.13:5060(547)
SIP/2.0 407 Proxy Authentication Required

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-d4cb6745;received=71.139.191.159

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 101 INVITE

Server: Gafachi UAS v110.08

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE

Contact: sip:[email protected]

Proxy-Authenticate: Digest realm=“sip.gafachi.com”, nonce=“c59c3c44af419866”

Content-Length: 0

[1]->64.192.112.13:5060(439)
[1]->64.192.112.13:5060(439)
ACK sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-d4cb6745

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 101 ACK

Max-Forwards: 70

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 0

[1]->64.192.112.13:5060(1277)
[1]->64.192.112.13:5060(1277)
INVITE sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-eb62451

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected]

Remote-Party-ID: “Fax” sip:[my_username]@64.192.112.13;screen=yes;party=calling

Call-ID: [email protected]

CSeq: 102 INVITE

Max-Forwards: 70

Proxy-Authorization: Digest username="[my_username]",realm=“sip.gafachi.com",nonce=“c59c3c44af419866”,uri="sip:[email protected]”,algorithm=MD5,response=“c1854c82c3616a5205a270c05514efa0”

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

Expires: 240

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 446

Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER

Supported: x-sipura, replaces

Content-Type: application/sdp

v=0

o=- 67094905 67094905 IN IP4 192.168.1.31

s=-

c=IN IP4 192.168.1.31

t=0 0

m=audio 16396 RTP/AVP 0 2 4 8 18 96 97 98 100 101

a=rtpmap:0 PCMU/8000

a=rtpmap:2 G726-32/8000

a=rtpmap:4 G723/8000

a=rtpmap:8 PCMA/8000

a=rtpmap:18 G729a/8000

a=rtpmap:96 G726-40/8000

a=rtpmap:97 G726-24/8000

a=rtpmap:98 G726-16/8000

a=rtpmap:100 NSE/8000

a=fmtp:100 192-193

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=ptime:20

a=sendrecv

[1]<<64.192.112.13:5060(405)
[1]<<64.192.112.13:5060(405)
SIP/2.0 100 Trying

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-eb62451;received=71.139.191.159

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected]

Call-ID: [email protected]

CSeq: 102 INVITE

Server: Gafachi UAS v110.08

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE

Contact: sip:[email protected]

Content-Length: 0

[1]<<64.192.112.13:5060(715)
[1]<<64.192.112.13:5060(715)
SIP/2.0 180 Ringing

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-eb62451;received=71.139.191.159

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 102 INVITE

Server: Gafachi UAS v110.08

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE

Contact: sip:[email protected]

Content-Type: application/sdp

Content-Length: 236

v=0

o=root 1022670786 1022670786 IN IP4 67.216.36.2

s=session

c=IN IP4 67.216.36.2

t=0 0

m=audio 48056 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=silenceSupp:off - - - -

a=ptime:20

[1:0]ENC INIT 0
[1:0]RTP Tx Up (pt=0->43d82402:48056)
[1:0]RTCP Tx Up
CC:CallProgress
[1:0]RTP Rx 1st PKT @16396(2)
[1:0]DEC INIT 0
[1]AUD:FAX Event=2
[1:0]ENC INIT 0
[1]<<64.192.112.13:5060(710)
[1]<<64.192.112.13:5060(710)
SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-eb62451;received=71.139.191.159

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 102 INVITE

Server: Gafachi UAS v110.08

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE

Contact: sip:[email protected]

Content-Type: application/sdp

Content-Length: 236

v=0

o=root 1022670786 1022670787 IN IP4 67.216.36.2

s=session

c=IN IP4 67.216.36.2

t=0 0

m=audio 48056 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=silenceSupp:off - - - -

a=ptime:20

[1]->64.192.112.13:5060(639)
[1]->64.192.112.13:5060(639)
ACK sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-32f03e1e

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 102 ACK

Max-Forwards: 70

Proxy-Authorization: Digest username="[my_username]",realm=“sip.gafachi.com",nonce=“c59c3c44af419866”,uri="sip:[email protected]”,algorithm=MD5,response=“c1854c82c3616a5205a270c05514efa0”

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 0

[1:0]RTP Tx Dn
[1:0]ENC INIT 0
[1:0]RTP Tx Up (pt=0->43d82402:48056)
CC:Remote Resume
CC:Connected
[1:0]CC:ALLOC T38 0
[1]CC:Force T.38 FAX
[1]->64.192.112.13:5060(1046)
[1]->64.192.112.13:5060(1046)
INVITE sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-fe3da6b6

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Remote-Party-ID: “Fax” sip:[my_username]@64.192.112.13;screen=yes;party=calling

Call-ID: [email protected]

CSeq: 103 INVITE

Max-Forwards: 70

Proxy-Authorization: Digest username="[my_username]",realm=“sip.gafachi.com",nonce=“c59c3c44af419866”,uri="sip:[email protected]”,algorithm=MD5,response=“c1854c82c3616a5205a270c05514efa0”

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

Expires: 30

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 269

Content-Type: application/sdp

v=0

o=- 67095485 67095485 IN IP4 192.168.1.31

s=-

c=IN IP4 192.168.1.31

t=0 0

m=image 16396 udptl t38

a=T38FaxVersion:0

a=T38MaxBitRate:14400

a=T38FaxRateManagement:transferredTCF

a=T38FaxMaxBuffer:200

a=T38FaxMaxDatagram:200

a=T38FaxUdpEC:t38UDPRedundancy

[1]<<64.192.112.13:5060(758)
[1]<<64.192.112.13:5060(758)
SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-fe3da6b6;received=71.139.191.159

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 103 INVITE

Server: Gafachi UAS v110.08

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE

Contact: sip:[email protected]

Content-Type: application/sdp

Content-Length: 283

v=0

o=root 1022670786 1022670788 IN IP4 67.216.36.2

s=session

c=IN IP4 67.216.36.2

t=0 0

m=image 48058 udptl t38

a=T38FaxVersion:0

a=T38FaxRateManagement:transferredTCFlocalTCF

a=T38FaxUdpEC:t38UDPFEC

a=T38FaxMaxBufferSize:2000

a=T38MaxDatagram:512

a=T38FaxMaxRate:14400

[1]->64.192.112.13:5060(639)
[1]->64.192.112.13:5060(639)
ACK sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 192.168.1.31:5061;branch=z9hG4bK-46f1970a

From: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

To: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 103 ACK

Max-Forwards: 70

Proxy-Authorization: Digest username="[my_username]",realm=“sip.gafachi.com",nonce=“c59c3c44af419866”,uri="sip:[email protected]”,algorithm=MD5,response=“c1854c82c3616a5205a270c05514efa0”

Contact: “Fax” sip:[my_username]@192.168.1.31:5061

User-Agent: Linksys/SPA2102-5.2.3

Content-Length: 0

SIP:Peer Confirm T38
SIP:Peer Confirm T38
[1:0]RTP Rx Dn
T38: StartRx
[1]FM Start RxTx (c=00244bf0)
T38 Decode UDPTL error
[1:0]RTP Tx Dn
[1] T38 Redundancy 1
T38: StartTx
[1]FM 00000010 Tx T38: i.no_signal
[1:0]ENC INIT 250
[1:0]RTP Tx Up (pt=250->43d82402:48058)
CC:Remote Resume
[1:0]RTP Rx Up
[1]FM 00000030 Tx T38: i.no_signal
T38 Decode UDPTL error
[1]FM 00000050 Tx T38: i.no_signal
T38 Decode UDPTL error
[1]FM 00000070 Tx T38: i.no_signal
T38 Decode UDPTL error
[1]FM 00000090 Tx T38: i.no_signal
T38 Decode UDPTL error
T38: duplicate packet received seq=0
T38: duplicate packet received seq=0
T38: duplicate packet received seq=0
[1]FM 00013280 Rx T38: i.v21_preamble
T38: duplicate packet received seq=2
T38: duplicate packet received seq=2
T38: duplicate packet received seq=2
[1]FM 00014720 Rx T38: d.v21 . . .
[1]FM 00014720 Rx T38: d.hdlc_fcs_OK
[1]FM 00014910 Mod NSF Frame [13]: ff 03 20 ad 00 51 00 00 00 00 00 9c df
T38: duplicate packet received seq=4
T38: duplicate packet received seq=4
T38: duplicate packet received seq=4
[1]FM 00015400 Rx T38: d.v21 . . .
[1]FM 00015400 Rx T38: d.hdlc_fcs_OK
T38: duplicate packet received seq=6
T38: duplicate packet received seq=6
T38: duplicate packet received seq=6
[1]FM 00015920 Mod CSI Frame [25]: ff 03 40 37 36 36 37 20 38 37 32 20 38 30 34 20 20 20 20 20 20 20 20 27 06
[1]FM 00015920 Rx T38: d.v21 . . .
[1]FM 00015920 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00016510 Mod DIS Frame [15]: ff 13 80 00 ee f8 00 80 92 80 80 80 00 60 50
[1]FM 00017190 Tx T38: i.v21_preamble
[1]FM 00018310 Tx T38: d.v21 . . .
[1]FM 00018450 DCS: 1.5.0.2.0.0.0.0 v17_14400
[1]FM 00018450 Dem DCS Frame [ 8]: ff 13 83 00 e2 78 6c 8e
[1]FM 00018450 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00018470 Tx T38: i.no_signal
[1]FM 00018480 Dem Modulation v17_14400_long_training
[1]FM 00018490 Tx T38: i.v17_14400_long_training
[1]FM 00020050 Tx T38: d.v17_14400 . . .
[1]FM 00021460 Z:2420
[1]FM 00021650 Dem Tf= 1682, Cf= 91, Ag= 1808, Qc= 0, Di= 0, Do= 0
[1]FM 00021650 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00021670 Tx T38: i.no_signal
T38: duplicate packet received seq=7
T38: duplicate packet received seq=7
T38: duplicate packet received seq=7
[1]FM 00023260 Rx T38: i.v21_preamble
T38: duplicate packet received seq=9
T38: duplicate packet received seq=9
T38: duplicate packet received seq=9
[1]FM 00024560 Rx T38: d.v21 . . .
[1]FM 00024560 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00024580 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[1]FM 00025310 Tx T38: i.v21_preamble
[1]FM 00026450 Tx T38: d.v21 . . .
[1]FM 00026570 DCS: 1.4.0.2.0.0.0.0 v17_12000
[1]FM 00026570 Dem DCS Frame [ 8]: ff 13 83 00 ea 78 ac 40
[1]FM 00026570 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00026590 Tx T38: i.no_signal
[1]FM 00026610 Dem Modulation v17_12000_long_training
[1]FM 00026610 Tx T38: i.v17_12000_long_training
[1]FM 00028190 Tx T38: d.v17_12000 . . .
[1]FM 00029590 Z:2020
[1]FM 00029790 Dem Tf= 1510, Cf= 82, Ag= 1863, Qc= 0, Di= 0, Do= 0
[1]FM 00029790 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00029810 Tx T38: i.no_signal
T38: duplicate packet received seq=10
T38: duplicate packet received seq=10
T38: duplicate packet received seq=10
[1]FM 00031380 Rx T38: i.v21_preamble
T38: duplicate packet received seq=12
T38: duplicate packet received seq=12
T38: duplicate packet received seq=12
[1]FM 00032660 Rx T38: d.v21 . . .
[1]FM 00032660 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00032680 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[1]FM 00033330 Tx T38: i.v21_preamble
[1]FM 00034470 Tx T38: d.v21 . . .
[1]FM 00034600 DCS: 1.3.0.2.0.0.0.0 v29_9600
[1]FM 00034600 Dem DCS Frame [ 8]: ff 13 83 00 c6 78 3f ca
[1]FM 00034610 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00034630 Dem Modulation v29_9600_training
[1]FM 00034630 Tx T38: i.no_signal
[1]FM 00034650 Tx T38: i.v29_9600_training
[1]FM 00035050 Tx T38: d.v29_9600 . . .
[1]FM 00036440 Z:1620
[1]FM 00036640 Dem Tf= 785, Cf= 244, Ag= 1602, Qc= 0, Di= 0, Do= 0
[1]FM 00036650 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00036670 Tx T38: i.no_signal
T38: duplicate packet received seq=13
T38: duplicate packet received seq=13
T38: duplicate packet received seq=13
[1]FM 00037640 Rx T38: i.v21_preamble
[1]FM 00038920 Rx T38: d.v21 . . .
[1]FM 00038920 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00038940 Mod CFR Frame [ 5]: ff 13 84 ea 7d
[1]FM 00039260 Dem Modulation v29_9600_training
[1]FM 00039710 Tx T38: i.v29_9600_training
[1]FM 00039730 Tx T38: d.v29_9600 . . .
[1]FM 00066430 Dem Tf= 2090, Cf= 8255, Ag= 1610, Qc=63238, Di= 0, Do= 0
[1]FM 00066450 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00066470 Tx T38: i.no_signal
[1]FM 00066810 Tx T38: i.v21_preamble
[1]FM 00067950 Tx T38: d.v21 . . .
[1]FM 00067970 Dem EOP Frame [ 5]: ff 13 2f 33 66
[1]FM 00067990 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00068010 Tx T38: i.no_signal
T38: duplicate packet received seq=16
T38: duplicate packet received seq=16
T38: duplicate packet received seq=16
[1]FM 00069320 Rx T38: i.v21_preamble
T38: duplicate packet received seq=18
T38: duplicate packet received seq=18
T38: duplicate packet received seq=18
[1]FM 00070600 Rx T38: d.v21 . . .
[1]FM 00070600 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00070620 Mod RTN Frame [ 5]: ff 13 4c ae 37
[1]FM 00071290 Tx T38: i.v21_preamble
[1]FM 00072430 Tx T38: d.v21 . . .
[1]FM 00072530 DCS: 1.2.0.2.0.0.0.0 v29_7200
[1]FM 00072530 Dem DCS Frame [ 8]: ff 13 83 00 ce 78 ff 04
[1]FM 00072550 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00072570 Dem Modulation v29_7200_training
[1]FM 00072570 Tx T38: i.no_signal
[1]FM 00072590 Tx T38: i.v29_7200_training
[1]FM 00072990 Tx T38: d.v29_7200 . . .
[1]FM 00074370 Z:1200
[1]FM 00074590 Dem Tf= 1111, Cf= 241, Ag= 1663, Qc=63238, Di= 0, Do= 0
[1]FM 00074590 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00074610 Tx T38: i.no_signal
T38: duplicate packet received seq=19
T38: duplicate packet received seq=19
T38: duplicate packet received seq=19
[1]FM 00075580 Rx T38: i.v21_preamble
T38: duplicate packet received seq=21
T38: duplicate packet received seq=21
T38: duplicate packet received seq=21
[1]FM 00076860 Rx T38: d.v21 . . .
[1]FM 00076860 Rx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00076880 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[1]FM 00077550 Tx T38: i.v21_preamble
[1]FM 00078690 Tx T38: d.v21 . . .
[1]FM 00078790 DCS: 1.1.0.2.0.0.0.0 v27_4800
[1]FM 00078790 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[1]FM 00078810 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00078830 Tx T38: i.no_signal
[1]FM 00078850 Dem Modulation v27_4800_training
[1]FM 00078850 Tx T38: i.v27_4800_training
[1]FM 00083860 Dem Tf= 1111, Cf= 241, Ag= 1663, Qc=63238, Di= 0, Do= 0
[1]FM 00083870 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00083890 Tx T38: i.no_signal
[1]FM 00084550 Tx T38: i.v21_preamble
[1]FM 00085690 Tx T38: d.v21 . . .
[1]FM 00085820 DCS: 1.1.0.2.0.0.0.0 v27_4800
[1]FM 00085820 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[1]FM 00085830 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00085850 Dem Modulation v27_4800_training
[1]FM 00085850 Tx T38: i.no_signal
[1]FM 00085870 Tx T38: i.v27_4800_training
[1]FM 00090860 Dem Tf= 1111, Cf= 241, Ag= 1663, Qc=63238, Di= 0, Do= 0
[1]FM 00090870 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00090890 Tx T38: i.no_signal
[1]FM 00091550 Tx T38: i.v21_preamble
[1]FM 00092690 Tx T38: d.v21 . . .
[1]FM 00092810 DCS: 1.1.0.2.0.0.0.0 v27_4800
[1]FM 00092810 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[1]FM 00092830 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00092850 Dem Modulation v27_4800_training
[1]FM 00092850 Tx T38: i.no_signal
[1]FM 00092870 Tx T38: i.v27_4800_training
[1]FM 00097860 Dem Tf= 1111, Cf= 241, Ag= 1663, Qc=63238, Di= 0, Do= 0
[1]FM 00097870 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00097890 Tx T38: i.no_signal
[1]FM 00098530 Tx T38: i.v21_preamble
[1]FM 00099670 Tx T38: d.v21 . . .
[1]FM 00099780 DCS: 1.1.0.2.0.0.0.0 v27_4800
[1]FM 00099780 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[1]FM 00099810 Tx T38: d.hdlc_fcs_OK_sig_end
[1]FM 00099820 Dem Modulation v27_4800_training
[1]FM 00099830 Tx T38: i.no_signal
[1]FM 00099850 Tx T38: i.v27_4800_training
[1]FM 00104830 Dem Tf= 1111, Cf= 241, Ag= 1663, Qc=63238, Di= 0, Do= 0
[1]FM 00104830 Tx T38: d.t4_non_ecm_sig_end
[1]FM 00104850 Tx T38: i.no_signal
[1]<<64.192.112.13:5060(431)
[1]<<64.192.112.13:5060(431)
BYE sip:[my_username]@192.168.1.31:5061 SIP/2.0

Via: SIP/2.0/UDP 64.192.112.13:5060;branch=z9hG4bK9bfcfee9

From: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

To: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

Contact: sip:[email protected]

Call-ID: [email protected]

CSeq: 102 BYE

User-Agent: Gafachi UAC v110.08

Max-Forwards: 70

Content-Length: 0

[1]->64.192.112.13:5060(333)
[1]->64.192.112.13:5060(333)
SIP/2.0 200 OK

To: “Fax” sip:[my_username]@64.192.112.13;tag=1e54e8fcc09e6b5o1

From: sip:[email protected];tag=gss8ec360cd664f471d104d56aa41f73823

Call-ID: [email protected]

CSeq: 102 BYE

Via: SIP/2.0/UDP 64.192.112.13:5060;branch=z9hG4bK9bfcfee9

Server: Linksys/SPA2102-5.2.3

Content-Length: 0

CC:Ended
FM Stop RxTx Forced
T38: StopRx
T38: StopTx
[1]FM Alert Stop RxTx (c=00244bf0;a=1)
[1:0]AUD Rel Call
[1]On Hook

If I had to take a complete wild guess… and I’ll be the first to admit that my knowledge of the SIP protocol is not exactly top notch.

However, I do know enough to know that the way the protocol is designed causes HUGE problems with NAT (kinda like FTP).

seeing all those SIP packets in that log you pasted… I see alot of 192.168.x.x IPs IN the sip packets. I;m wondering if Gafachi is seeing these addresses and thinking that thats the address they should be sending data to for the RTP / T.38 Re-INVITE.

I’;m also seeing in that dump… alot of “no_signals”… on the T.38 lines… this would kind of support my theory of it being a NAT problem… if your ATA is sending a ReINVITE for t.38 and giving it a 192.168.x.x address… this probably isn;t going to work since they obviously can;t connect back to that address.

If you are able to… try plugging the SPA2102 directly into an internet connection with a real IP address and see if it works… if it does you know its a NAT problem…

the SPA has a million settings on it as well for NAT… there is probably also an option in there to set your NAT IP… but then you’ll also need to worry about ports being forwarded from your firewall and stuff… best bet is to try it on a real IP and see how that works first.

@Jperry: I am no expert, but I want to give it a look. Please, just send a full capture (Wireshark .cap file) wich includes:

  1. A complete sip call outbound
  2. A complete sip call inbound
  3. A fax from you to somebody (trying to use t.38)
  4. A fax from somebody to you (trying to use t.38)

You can record these in a single .CAP, or many smaller ones. Be sure you are the only one using your PBX, and therer is not much traffic on your LAN/WAN to reduce the size of the capture.

I’m not sure you can upload attachements here, but feel free to send them trough EMaaill: just remove the BUZZ from the adress below:
[email protected] BUzz .com

As a test, from mwatson’s insightful guess about NAT issues,
I changed the SIP tab’s
Substitute VIA Addr, Insert VIA rport, Send Resp To Src Port, to Yes
That made it work for one fax, but not again.
So I set all that back to No, then re-arranged it to go through Asterisk:

I changed things around so now it should be like mwatson’s setup:
I created the udptl.conf as
[general]
udptlstart=4000
udptlend=4999
T38FaxUdpEC = t38UDPRedundancy
T38FaxMaxDatagram = 400
udptlfecentries = 1
udptlfecspan = 3

and in sip_general_custom.conf I put
t38pt_udptl = yes

I then rebooted the computer.
So, now it is going:
spa2102 -> trixbox/FreePBX -> DSL -> Gafachi > POTS-fax

Around trying 7200 the fax machine spits out a blank page,
but I never get a good page.

spa syslog:

Calling:[email protected]:0
[0:0]AUD ALLOC CALL (port=16398)
[0:0]RTP Rx Up
CC:Ringback
[0:0]RTP Rx Dn
[0:0]ENC INIT 0
[0:0]RTP Tx Up (pt=0->c0a801c8:12764)
[0:0]RTCP Tx Up
CC:CallProgress
[0:0]RTP Rx Up
[0]AUD:FAX Event=2
[0:0]ENC INIT 0
[0:0]RTP Rx 1st PKT @16398(2)
[0:0]DEC INIT 0
[0:0]RTP Tx Dn
[0:0]ENC INIT 0
[0:0]RTP Tx Up (pt=0->c0a801c8:12764)
CC:Remote Resume
CC:Connected
[0:0]CC:ALLOC T38 0
[0]CC:Force T.38 FAX
SIP:Peer Confirm T38
SIP:Peer Confirm T38
[0:0]RTP Rx Dn
T38: StartRx
[0]FM Start RxTx (c=0023f178)
T38 Decode UDPTL error
[0:0]RTP Tx Dn
[0] T38 Redundancy 1
T38: StartTx
[0:0]ENC INIT 250
[0:0]RTP Tx Up (pt=250->c0a801c8:4130)
CC:Remote Resume
[0:0]RTP Rx Up
[0]FM 00000020 Tx T38: i.no_signal
[0]FM 00000040 Tx T38: i.no_signal
[0]FM 00000060 Tx T38: i.no_signal
[0]FM 00000080 Tx T38: i.no_signal
[0]FM 00000100 Tx T38: i.no_signal
[0]FM 00009750 Rx T38: i.v21_preamble
[0]FM 00013160 Rx T38: i.v21_preamble
[0]FM 00014570 Rx T38: d.v21 . . .
[0]FM 00014570 Rx T38: d.hdlc_fcs_OK
[0]FM 00014790 Mod NSF Frame [13]: ff 03 20 ad 00 51 00 00 00 00 00 9c df
[0]FM 00015250 Rx T38: d.v21 . . .
[0]FM 00015260 Rx T38: d.hdlc_fcs_OK
[0]FM 00015750 Mod CSI Frame [25]: ff 03 40 37 36 36 37 20 38 37 32 20 38 30 34 20 20 20 20 20 20 20 20 27 06
[0]FM 00015780 Rx T38: d.v21 . . .
[0]FM 00015780 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00016340 Mod DIS Frame [15]: ff 13 80 00 ee f8 00 80 92 80 80 80 00 60 50
[0]FM 00017020 Tx T38: i.v21_preamble
[0]FM 00018160 Tx T38: d.v21 . . .
[0]FM 00018250 DCS: 1.5.0.2.0.0.0.0 v17_14400
[0]FM 00018250 Dem DCS Frame [ 8]: ff 13 83 00 e2 78 6c 8e
[0]FM 00018280 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00018300 Dem Modulation v17_14400_long_training
[0]FM 00018300 Tx T38: i.no_signal
[0]FM 00018320 Tx T38: i.v17_14400_long_training
[0]FM 00019880 Tx T38: d.v17_14400 . . .
[0]FM 00021280 Z:2420
[0]FM 00021480 Dem Tf= 2161, Cf= 101, Ag= 1053, Qc= 0, Di= 0, Do= 0
[0]FM 00021480 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00021500 Tx T38: i.no_signal
[0]FM 00023210 Rx T38: i.v21_preamble
[0]FM 00024500 Rx T38: d.v21 . . .
[0]FM 00024500 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00024520 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[0]FM 00025260 Tx T38: i.v21_preamble
[0]FM 00026380 Tx T38: d.v21 . . .
[0]FM 00026510 DCS: 1.4.0.2.0.0.0.0 v17_12000
[0]FM 00026510 Dem DCS Frame [ 8]: ff 13 83 00 ea 78 ac 40
[0]FM 00026520 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00026540 Dem Modulation v17_12000_long_training
[0]FM 00026540 Tx T38: i.no_signal
[0]FM 00026560 Tx T38: i.v17_12000_long_training
[0]FM 00028120 Tx T38: d.v17_12000 . . .
[0]FM 00029520 Z:2020
[0]FM 00029710 Dem Tf= 1762, Cf= 117, Ag= 1054, Qc= 0, Di= 0, Do= 0
[0]FM 00029720 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00029740 Tx T38: i.no_signal
[0]FM 00031460 Rx T38: i.v21_preamble
[0]FM 00032750 Rx T38: d.v21 . . .
[0]FM 00032750 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00032770 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[0]FM 00033480 Tx T38: i.v21_preamble
[0]FM 00034620 Tx T38: d.v21 . . .
[0]FM 00034730 DCS: 1.3.0.2.0.0.0.0 v29_9600
[0]FM 00034730 Dem DCS Frame [ 8]: ff 13 83 00 c6 78 3f ca
[0]FM 00034760 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00034780 Dem Modulation v29_9600_training
[0]FM 00034780 Tx T38: i.no_signal
[0]FM 00034800 Tx T38: i.v29_9600_training
[0]FM 00035180 Tx T38: d.v29_9600 . . .
[0]FM 00036560 Z:1620
[0]FM 00036760 Dem Tf= 1631, Cf= 238, Ag= 927, Qc= 0, Di= 0, Do= 0
[0]FM 00036760 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00036780 Tx T38: i.no_signal
[0]FM 00037910 Rx T38: i.v21_preamble
[0]FM 00039200 Rx T38: d.v21 . . .
[0]FM 00039200 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00039220 Mod FTT Frame [ 5]: ff 13 44 e6 bb
[0]FM 00039920 Tx T38: i.v21_preamble
[0]FM 00041060 Tx T38: d.v21 . . .
[0]FM 00041170 DCS: 1.2.0.2.0.0.0.0 v29_7200
[0]FM 00041170 Dem DCS Frame [ 8]: ff 13 83 00 ce 78 ff 04
[0]FM 00041200 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00041210 Dem Modulation v29_7200_training
[0]FM 00041220 Tx T38: i.no_signal
[0]FM 00041240 Tx T38: i.v29_7200_training
[0]FM 00041620 Tx T38: d.v29_7200 . . .
[0]FM 00042970 Z:1200
[0]FM 00043190 Dem Tf= 1836, Cf= 230, Ag= 941, Qc= 0, Di= 0, Do= 0
[0]FM 00043200 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00043220 Tx T38: i.no_signal
[0]FM 00044320 Rx T38: i.v21_preamble
[0]FM 00045610 Rx T38: d.v21 . . .
[0]FM 00045610 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00045630 Mod CFR Frame [ 5]: ff 13 84 ea 7d
[0]FM 00046000 Dem Modulation v29_7200_training
[0]FM 00046440 Tx T38: i.v29_7200_training
[0]FM 00046460 Tx T38: d.v29_7200 . . .
[0]FM 00093940 Dem Tf= 3151, Cf= 234, Ag= 950, Qc=228, Di= 0, Do= 0
[0]FM 00093960 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00093980 Tx T38: i.no_signal
[0]FM 00094320 Tx T38: i.v21_preamble
[0]FM 00095440 Tx T38: d.v21 . . .
[0]FM 00095460 Dem EOP Frame [ 5]: ff 13 2f 33 66
[0]FM 00095480 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00095500 Tx T38: i.no_signal
[0]FM 00096930 Rx T38: i.v21_preamble
[0]FM 00098210 Rx T38: d.v21 . . .
[0]FM 00098210 Rx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00098230 Mod RTN Frame [ 5]: ff 13 4c ae 37
[0]FM 00098900 Tx T38: i.v21_preamble
[0]FM 00100020 Tx T38: d.v21 . . .
[0]FM 00100130 DCS: 1.1.0.2.0.0.0.0 v27_4800
[0]FM 00100130 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[0]FM 00100160 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00100180 Tx T38: i.no_signal
[0]FM 00100190 Dem Modulation v27_4800_training
[0]FM 00100200 Tx T38: i.v27_4800_training
[0]FM 00105200 Dem Tf= 3151, Cf= 234, Ag= 950, Qc=228, Di= 0, Do= 0
[0]FM 00105200 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00105220 Tx T38: i.no_signal
[0]FM 00105880 Tx T38: i.v21_preamble
[0]FM 00107020 Tx T38: d.v21 . . .
[0]FM 00107140 DCS: 1.1.0.2.0.0.0.0 v27_4800
[0]FM 00107140 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[0]FM 00107140 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00107160 Tx T38: i.no_signal
[0]FM 00107170 Dem Modulation v27_4800_training
[0]FM 00107180 Tx T38: i.v27_4800_training
[0]FM 00112180 Dem Tf= 3151, Cf= 234, Ag= 950, Qc=228, Di= 0, Do= 0
[0]FM 00112180 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00112200 Tx T38: i.no_signal
[0]FM 00112860 Tx T38: i.v21_preamble
[0]FM 00113980 Tx T38: d.v21 . . .
[0]FM 00114110 DCS: 1.1.0.2.0.0.0.0 v27_4800
[0]FM 00114110 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[0]FM 00114140 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00114150 Dem Modulation v27_4800_training
[0]FM 00114160 Tx T38: i.no_signal
[0]FM 00114180 Tx T38: i.v27_4800_training
[0]FM 00119160 Dem Tf= 3151, Cf= 234, Ag= 950, Qc=228, Di= 0, Do= 0
[0]FM 00119160 Tx T38: d.t4_non_ecm_sig_end
[0]FM 00119180 Tx T38: i.no_signal
[0]FM 00119880 Tx T38: i.v21_preamble
[0]FM 00121020 Tx T38: d.v21 . . .
[0]FM 00121140 DCS: 1.1.0.2.0.0.0.0 v27_4800
[0]FM 00121140 Dem DCS Frame [ 8]: ff 13 83 00 ca 78 9f 63
[0]FM 00121160 Tx T38: d.hdlc_fcs_OK_sig_end
[0]FM 00121180 Dem Modulation v27_4800_training
[0]FM 00121180 Tx T38: i.no_signal
[0]FM 00121200 Tx T38: i.v27_4800_training
CC:Ended
FM Stop RxTx Forced
T38: StopRx
T38: StopTx
[0]FM Alert Stop RxTx (c=0023f178;a=1)
[0:0]AUD Rel Call
[0]On Hook

using a grandstream HT286 with gafachi. i did add ‘t38pt_udptl=yes’ to /etc/asterisk/sip_general_custom.conf. i had to stick with canreinvite=no in the extension and configured the ATA for autodetect. i fired up ethereal on the wan interface while sending a fax and saw the reinvite and the subsequent HDLC packets…

I dont intend to hijack
Sorry for the really really really really really stupid qestion here
I understand that asterisk 1.2 has no t38 support
I do have some clients who would want to use faxing over asterisk though, but they are still under asterisk 1.2
will adding these lines work or will I just be waisting my time?

Just thought I’d send a friendly reminder/request for that guide :slight_smile:

Thanks,

Michael

So has anyone found a definitive guide that says exactly what we should do to get T.38 fax working over Gafachi? Kinda hard to find!

if I remember I’ll write one up tonight…

I’ve helped a friend with a gafachi fax account a couple weeks ago. IIRC there is nothing special about doing it for gafachi vs. any other provider (that supports T.38)