[asterisk-users] debugging T.38 issues

Wed Oct 15 02:23:45 CDT 2014

I don't know if this may help 
https://www.escaux.com/docs/DRD_T38Support_AdminGuide.html assuming you 
can enable T.38 on the Sangoma Netborder, then you can turn off the 
faxgateway option.

Larry.

On 15/10/2014 3:19 PM, Larry Moore wrote:
> It's been a while since I played with a Cisco SPA8800 with T.38 and with
> incoming faxes. There were settings in the SIP configurations for the
> SPA8800 to get it working with T.38 with asterisk, I don't know if the
> same will apply for this device.
>
> If memory serves me you don't need, or perhaps, shouldn't use the T.38
> Gateway feature for the incoming call unless you are expecting your
> endpoint to be running T.30, in your case the SPA-112.
>
> A quick glance over the data sheet for this device suggests it supports
> T.38 thus providing you have T.38 enabled on the SPA-211 I would advise
> against attempting to use the gateway feature for the incoming call.
>
> In my experience Cisco use UDP redundancy and the default value is 1,
> you may want to experiment with this value and set it to 3. You may want
> to adjust the values in asterisk's udptl.conf by setting udptlfecentries
> & udptlfecspan to the same value, don't forget to restart asterisk after
> the change, I can't remember if you can force an unload and reload of
> the udptl module in asterisk.
>
> You have not provided any information relating to the SPA-112's
> configuration in sip.conf so here are some settings I have;
>
> [9003]
> ; Cisco SPA8800 FXS Port 3
> ; Analogue FAX Modem attached
> type=friend
> call-limit=2
> qualify=yes
> canreinvite=no
> ;directmedia=no
> host=dynamic
> context=FAX-T38
> faxdetect=no
> ;t38pt_udptl=yes,redundancy,maxdatagram=400
>
> I can't recall if I tested receiving a fax using G711 and used the
> faxgateway option when directing the call to the SPA8800
>
> Larry.
>
>
>
> On 14/10/2014 8:59 PM, Frederic Van Espen wrote:
>> Hello list,
>>
>> We're currently facing some issues concerning T.38 gateway faxing.
>> This is a device used almost exclusively for receiving faxes. Calls
>> are incoming to asterisk on a SIP trunk (sangoma netborder) using
>> G711A. Gateway mode is activated in the asterisk dialplan towards a
>> Cisco SPA 112 running firmware 1.3.5. We are using asterisk 1.8.13.0
>> with the T.38 gateway patch applied (I know I know, we should move to
>> asterisk 11. I'm trying that tonight after business hours).
>>
>> The issue we're seeing is that faxes incoming from some specific fax
>> machines consistenly fail. I have indentified 2 types of failures:
>> - Incoming call is sent to SPA112, reinvite to T.38 is initiated and
>> accepted. One T.38 packet is sent from the SPA112 to asterisk
>> (t30ind: no-signal, see pcap output below) followed by 20 seconds of
>> nothingness and then the call is hung up.
>> - Incoming call is sent to SPA112, reinvite to T.38 is initiated and
>> accepted. A number of T.38 packets is sent from the SPA112 to asterisk
>> (it repeats NSF,CSI,DIS signals 3 times) followed ba call hangup.
>>
>> In none of the above 2 cases do I see T.38 packets flowing from
>> asterisk to the SPA112.
>>
>> In the logs I see these things that indicate T.38 gateway being started:
>> [Oct 14 14:16:17] DEBUG[11426] res_fax.c: SIP/SDSD0005-0007cb05 is
>> attempting to negotiate T.38 but SIP/SOV20001-0007cb04 does not
>> support it
>> [Oct 14 14:16:17] DEBUG[11426] res_fax.c: starting T.38 gateway for
>> T.38 channel SIP/SDSD0005-0007cb05 and G.711 channel
>> SIP/SOV20001-0007cb04
>> [Oct 14 14:16:17] DEBUG[11426] res_fax.c: Requesting a new FAX session
>> from 'Spandsp FAX Driver'.
>> [Oct 14 14:16:17] DEBUG[11426] res_fax.c: channel
>> 'SIP/SOV20001-0007cb04' using FAX session '660'
>> [Oct 14 14:16:17] DEBUG[11426] chan_sip.c: T38 state changed to 3 on
>> channel SIP/SDSD0005-0007cb05
>>
>>
>> PCAP text output of 1st case:
>> 216.025063 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4877, Time=1179871936
>> 216.042133 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8641, Time=2227760
>> 216.045031 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4878, Time=1179872096
>> 216.062169 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8642, Time=2227920
>> 216.065031 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4879, Time=1179872256
>> 216.082161 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8643, Time=2228080
>> 216.085022 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4880, Time=1179872416
>> 216.102145 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8644, Time=2228240
>> 216.105045 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4881, Time=1179872576
>> 216.122158 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8645, Time=2228400
>> 216.125042 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4882, Time=1179872736
>> 216.142145 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8646, Time=2228560
>> 216.145043 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x6118CC28, Seq=4883, Time=1179872896
>> 216.146259 192.168.196.94 -> 192.168.196.3 SIP/SDP Request: INVITE
>> sip:0043767079 at 192.168.196.3:5060, with session description
>> 216.147280 192.168.196.3 -> 192.168.196.94 SIP Status: 100 Trying
>> 216.147993 192.168.196.3 -> 192.168.196.94 SIP/SDP Status: 200 OK,
>> with session description
>> 216.162166 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8647, Time=2228720
>> 216.182149 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8648, Time=2228880
>> 216.187971 28:92:4a:34:19:72 -> ac:f2:c5:35:ed:66 ARP Who has
>> 192.168.196.94? Tell 192.168.196.3
>> 216.188251 ac:f2:c5:35:ed:66 -> 28:92:4a:34:19:72 ARP 192.168.196.94
>> is at ac:f2:c5:35:ed:66
>> 216.203946 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x205734A, Seq=8649, Time=2229040
>> 216.229648 192.168.196.94 -> 192.168.196.3 SIP Request: ACK
>> sip:0043767079 at 192.168.196.3:5060
>> 216.234987 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00000 t30ind: no-signal
>> 237.503971 192.168.196.94 -> 192.168.196.3 SIP Request: BYE
>> sip:0043767079 at 192.168.196.3:5060
>> 237.505427 192.168.196.3 -> 192.168.196.94 SIP Status: 200 OK
>>
>>
>> PCAP text output of 2nd case:
>> 116.087359 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x62BD813F, Seq=59490, Time=2244459432
>> 116.094618 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1641, Time=1264160
>> 116.107393 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x62BD813F, Seq=59491, Time=2244459592
>> 116.113615 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1642, Time=1264320
>> 116.127400 192.168.196.3 -> 192.168.196.94 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x62BD813F, Seq=59492, Time=2244459752
>> 116.133640 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1643, Time=1264480
>> 116.143569 192.168.196.94 -> 192.168.196.3 SIP/SDP Request: INVITE
>> sip:0042406282 at 192.168.196.3:5060, with session description
>> 116.144319 192.168.196.3 -> 192.168.196.94 SIP Status: 100 Trying
>> 116.144887 192.168.196.3 -> 192.168.196.94 SIP/SDP Status: 200 OK,
>> with session description
>> 116.153850 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1644, Time=1264640
>> 116.173646 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1645, Time=1264800
>> 116.199127 192.168.196.94 -> 192.168.196.3 RTP PT=ITU-T G.711 PCMA,
>> SSRC=0x8EAA59B4, Seq=1646, Time=1264960
>> 116.229940 192.168.196.94 -> 192.168.196.3 SIP Request: ACK
>> sip:0042406282 at 192.168.196.3:5060
>> 116.237631 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00000 t30ind: no-signal
>> 116.747493 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00001 t30ind: ced
>> 116.757588 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00002 t30ind: no-signal
>> 117.387730 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00003 t30ind: v21-preamble
>> 117.397857 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00003 t30ind: v21-preamble
>> 117.407640 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00003 t30ind: v21-preamble
>> 117.435598 28:92:4a:34:19:72 -> ac:f2:c5:35:ed:66 ARP Who has
>> 192.168.196.94? Tell 192.168.196.3
>> 117.435899 ac:f2:c5:35:ed:66 -> 28:92:4a:34:19:72 ARP 192.168.196.94
>> is at ac:f2:c5:35:ed:66
>> 118.677727 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00004 data:v21: hdlc-data[FFC00400006AAA...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: NSF - Non-Standard Facilities)
>> 119.387802 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00005 data:v21: hdlc-data[FFC002CCCC6C2C...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: CSI - Called Subscriber Identification
>> - Number:042404633)
>> 119.817794 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00006 data:v21: hdlc-data[FFC80104771523...] (HDLC fragment 0)
>> hdlc-fcs-OK-sig-end (HDLC Reassembled: DIS - Digital Identification
>> Signal - DSR:ITU-T V.27 ter, V.29, and V.17)
>> 119.877246 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00007 t30ind: no-signal
>> 119.887540 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00008 t30ind: no-signal
>> 123.167804 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00009 t30ind: v21-preamble
>> 123.177713 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00009 t30ind: v21-preamble
>> 123.187801 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00009 t30ind: v21-preamble
>> 124.427832 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00010 data:v21: hdlc-data[FFC00400006AAA...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: NSF - Non-Standard Facilities)
>> 125.127833 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00011 data:v21: hdlc-data[FFC002CCCC6C2C...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: CSI - Called Subscriber Identification
>> - Number:042404633)
>> 125.567949 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00012 data:v21: hdlc-data[FFC80104771523...] (HDLC fragment 0)
>> hdlc-fcs-OK-sig-end (HDLC Reassembled: DIS - Digital Identification
>> Signal - DSR:ITU-T V.27 ter, V.29, and V.17)
>> 125.627325 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00013 t30ind: no-signal
>> 125.637723 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00014 t30ind: no-signal
>> 128.917917 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00015 t30ind: v21-preamble
>> 128.927809 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00015 t30ind: v21-preamble
>> 128.937894 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00015 t30ind: v21-preamble
>> 130.177960 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00016 data:v21: hdlc-data[FFC00400006AAA...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: NSF - Non-Standard Facilities)
>> 130.887932 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00017 data:v21: hdlc-data[FFC002CCCC6C2C...] (HDLC fragment 0)
>> hdlc-fcs-OK (HDLC Reassembled: CSI - Called Subscriber Identification
>> - Number:042404633)
>> 131.317940 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00018 data:v21: hdlc-data[FFC80104771523...] (HDLC fragment 0)
>> hdlc-fcs-OK-sig-end (HDLC Reassembled: DIS - Digital Identification
>> Signal - DSR:ITU-T V.27 ter, V.29, and V.17)
>> 131.377426 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00019 t30ind: no-signal
>> 131.387773 192.168.196.94 -> 192.168.196.3 T.38 UDP: UDPTLPacket
>> Seq=00020 t30ind: no-signal
>> 133.914404 ac:f2:c5:35:ed:66 -> 28:92:4a:34:19:72 ARP Who has
>> 192.168.196.3? Tell 192.168.196.94
>> 133.914427 28:92:4a:34:19:72 -> ac:f2:c5:35:ed:66 ARP 192.168.196.3 is
>> at 28:92:4a:34:19:72
>> 137.654538 ac:f2:c5:35:ed:66 -> ff:ff:ff:ff:ff:ff ARP Who has
>> 192.168.196.1? Tell 192.168.196.94
>> 157.053791 192.168.196.94 -> 192.168.196.3 SIP Request: BYE
>> sip:0042406282 at 192.168.196.3:5060
>> 157.055245 192.168.196.3 -> 192.168.196.94 SIP Status: 200 OK
>>
>>
>> Is there anyone with expertise or recommendations on this list? Do let
>> me know if there is any information missing.
>>
>> Thanks,
>>
>> Frederic
>>
>