[asterisk-users] debugging T.38 issues
Larry Moore
lmoore at omninet.net.au
Wed Oct 15 02:19:41 CDT 2014
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
>
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