Top part of Incoming fax messages to fax server are sometimes damaged

[dustycr]

Hello everyone,

we have the problem that sometimes incoming fax messages received by the fax server are damaged.
Its always the top part which is not readable so it seems like maybe there could be a problem with the first packets being received by the 3cx.

I attached a photo of the top part from one of the damaged fax messages we received.

(The red marked is censored afterwards from me)

Thanks in advance!

 

[cobaltit]

I agree, that looks like a picture of a damaged fax and I agree it could be a problem with the first packets being received by 3CX (along with a multitude of other possibilities). What I don't see is any mention of how the faxes are coming into the system (SIP, analog, PRI) and an actual question.

 

[dustycr]

Hello,
sorry for the lack background infos.

3CX is connected over a SIP Trunk from the german provider QSC.
Incoming Faxes will be transmitted mostly over t.38 as far i know.

OS: Debian (3CX Image)
3CX Version: 15.5.0
Enable G.711 to T.38 Fallback [BETA] is enabled.

Following the log from one of the damaged fax messages:

06/12/2018 10:34:27 AM - Stop call record for leg L:1403.2[Fax:88]
06/12/2018 10:34:27 AM - Removing leg L:1403.2[Fax:88]
06/12/2018 10:34:27 AM - L:1403.2[Fax:88]: Terminating targets, reason: SIP ;cause=200 ;text="User hangup"
06/12/2018 10:34:27 AM - Leg L:1403.2[Fax:88] is terminated: Cause: BYE from 127.0.0.1:5483
06/12/2018 10:34:27 AM - L:1403.2[Fax:88] got Terminated Recv Req BYE from 127.0.0.1:5483 tid=14f967395c87f534 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
BYE sip:[email protected]:5060 SIP/2.0
Via: SIP/2.0/UDP 127.0.0.1:5483;branch=z9hG4bK-524287-1---14f967395c87f534;rport=5483
Max-Forwards: 70
Contact: <sip:[email protected]:5483;rinstance=d98bf2f79028368c>
To: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
From: <sip:[email protected]:5060;user=fax>;tag=4041d210
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 2 BYE
User-Agent: 3CX Fax
Reason: SIP;text=User Hung Up
Content-Length: 0

06/12/2018 10:34:27 AM - L:1403.2[Fax:88] Sending: OnSendResp Send 200/BYE from 0.0.0.0:0 tid=14f967395c87f534 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
SIP/2.0 200 OK
Via: SIP/2.0/UDP 127.0.0.1:5483;branch=z9hG4bK-524287-1---14f967395c87f534;rport=5483
Contact: <sip:[email protected]:5060>
To: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
From: <sip:[email protected]:5060;user=fax>;tag=4041d210
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 2 BYE
Content-Length: 0

06/12/2018 10:33:42 AM - [CM503007]: Call(C:1403): Fax:88 has joined, contact <sip:[email protected]:5483>
06/12/2018 10:33:42 AM - L:1403.2[Fax:88] has joined to L:1403.1[Line:10001<<+1234567890]
06/12/2018 10:33:42 AM - Session 1089957 of leg L:1403.2[Fax:88] is connected
06/12/2018 10:33:42 AM - L:1403.2[Fax:88] got Connected.UAC Recv 200/INVITE from 127.0.0.1:5483 tid=323e997472e6f839 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
SIP/2.0 200 OK
Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---323e997472e6f839;rport=5060
Contact: <sip:[email protected]:5483;rinstance=d98bf2f79028368c>
To: <sip:[email protected]:5060;user=fax>;tag=4041d210
From: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 1 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE
Content-Type: application/sdp
Supported: replaces
User-Agent: 3CX Fax
Content-Length: 211

v=0
o=3cxVCE 842462416 1664449093 IN IP4 127.0.0.1
s=3cxVCE Audio Call
c=IN IP4 127.0.0.1
t=0 0
m=audio 12216 RTP/AVP 0 8 101
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
06/12/2018 10:33:42 AM - Remote SDP is set for leg L:1403.2[Fax:88]
06/12/2018 10:33:42 AM - Answer SDP arrived on Leg L:1403.2[Fax:88];
OnAnswer Recv 200/INVITE from 127.0.0.1:5483 tid=323e997472e6f839 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
SIP/2.0 200 OK
Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---323e997472e6f839;rport=5060
Contact: <sip:[email protected]:5483;rinstance=d98bf2f79028368c>
To: <sip:[email protected]:5060;user=fax>;tag=4041d210
From: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 1 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE
Content-Type: application/sdp
Supported: replaces
User-Agent: 3CX Fax
Content-Length: 211

v=0
o=3cxVCE 842462416 1664449093 IN IP4 127.0.0.1
s=3cxVCE Audio Call
c=IN IP4 127.0.0.1
t=0 0
m=audio 12216 RTP/AVP 0 8 101
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
06/12/2018 10:33:42 AM - L:1403.2[Fax:88] Sending: OnSendReq Send Req ACK from 0.0.0.0:0 tid=c7e9190e9b375b46 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
ACK sip:[email protected]:5483;rinstance=d98bf2f79028368c SIP/2.0
Via: SIP/2.0/ ;branch=z9hG4bK-524287-1---c7e9190e9b375b46;rport
Max-Forwards: 70
Contact: <sip:[email protected]:5060>
To: <sip:[email protected]:5060;user=fax>;tag=4041d210
From: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 1 ACK
Content-Length: 0

06/12/2018 10:33:42 AM - Provisional response arrived for session 1089957 of Leg L:1403.2[Fax:88]
06/12/2018 10:33:42 AM - L:1403.2[Fax:88] got Provisional Recv 180/INVITE from 127.0.0.1:5483 tid=323e997472e6f839 Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 127.0.0.1:5060;branch=z9hG4bK-524287-1---323e997472e6f839;rport=5060
Contact: <sip:[email protected]:5483;rinstance=d98bf2f79028368c>
To: <sip:[email protected]:5060;user=fax>;tag=4041d210
From: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 1 INVITE
User-Agent: 3CX Fax
Content-Length: 0

06/12/2018 10:33:42 AM - [CM503002]: Call(C:1403): Alerting Fax:88 by contact <sip:[email protected]:5483>
06/12/2018 10:33:42 AM - UacSession 1089957 has formed leg L:1403.2[Fax:88]
06/12/2018 10:33:42 AM - [CM503025]: Call(C:1403): Calling T:Fax:88@[Dev:sip:[email protected]:5483;rinstance=d98bf2f79028368c] for L:1403.1[Line:10001<<+1234567890]
06/12/2018 10:33:42 AM - Route to L:1403.2[Fax:88] sends Invite-OUT Send Req INVITE from 0.0.0.0:0 tid=542972222a68426f Call-ID=LfogbEtZd6hEr2io7HdgyQ..:
INVITE sip:[email protected]:5483;rinstance=d98bf2f79028368c SIP/2.0
Via: SIP/2.0/ ;branch=z9hG4bK-524287-1---542972222a68426f;rport
Max-Forwards: 70
Contact: <sip:[email protected]:5060>
To: <sip:[email protected]:5060;user=fax>
From: "+1234567890"<sip:[email protected]:5060;nf=e>;tag=8ae04c0e
Call-ID: LfogbEtZd6hEr2io7HdgyQ..
CSeq: 1 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE, UPDATE
Content-Type: application/sdp
Supported: replaces, timer
Content-Length: 329

v=0
o=3cxPS 33405442654732288 30682963851083777 IN IP4 127.0.0.1
s=3cxPS Audio call
c=IN IP4 127.0.0.1
t=0 0
m=audio 7108 RTP/AVP 0 8 9 3 18 101
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:9 G722/8000
a=rtpmap:3 GSM/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=sendrecv
06/12/2018 10:33:42 AM - L:1403.2[Fax:88]: SLA slot is acquired: 88#0 'idle'
06/12/2018 10:33:42 AM - Added leg L:1403.2[Fax:88]
06/12/2018 10:33:42 AM - [Flow] Call(C:1403): making call from L:1403.1[Line:10001<<+1234567890] to T:Fax:88@[Dev:sip:[email protected]:5483;rinstance=d98bf2f79028368c]
06/12/2018 10:33:42 AM - [CM503027]: Call(C:1403): From: Line:10001<<+1234567890 ("+1234567890" <sip:[email protected]:5060>)  to  T:Fax:88@[Dev:sip:[email protected]:5483;rinstance=d98bf2f79028368c]
06/12/2018 10:33:42 AM - [CM503004]: Call(C:1403): Route 1: from L:1403.1[Line:10001<<1234567890] to T:Fax:88@[Dev:sip:[email protected]:5483;rinstance=d98bf2f79028368c]
06/12/2018 10:33:42 AM - [Flow] Call(C:1403): has built target endpoint: Fax:88 for call from L:1403.1[Line:10001<<+1234567890]

What could be a cause of this problem, i already spoke with the provider and they told me that everything is looking fine from their site ...

 

[cobaltit]

I'd turn off the g.711 fallback. It looks like that call is g.711 only which really only works with near perfect internet connections. T.38 is supposed to resolve the issue with FoIP but while it works more reliable over less than perfect internet connections it introduces a problem with compatibility between different vendors T.38 implementations. This is why I always make customers either keep a POTS line or use our 'store-and-forward' fax adapters for reliable faxing. Anything else is just 'best effort'.

If you did receive the fax via T.38 you should see something like this:

From: <sip:[email protected]:5060;user=fax>;tag=b89cdf5e
Call-ID: QsAr_GbfeFg7Wz0mx-ofUA..
CSeq: 2 INVITE
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE
Content-Type: application/sdp
Supported: replaces
User-Agent: 3CX Fax
Content-Length: 260

v=0
o=3cxVCE 18446744073197996330 18446744073603197767 IN IP4 127.0.0.1
s=3cxVCE Audio Call
c=IN IP4 127.0.0.1
t=0 0
m=image 12108 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxRateManagement:transferredTCF
a=T38FaxUdpEC:t38UDPRedundancy

 

[dustycr]

Hi,

thanks for your answer!
We will try that.

When we disable the fallback option in the fax server and the other site doesn't support the t38 protocol the fax will fail correct ?

We receive about 80-100 Faxes a day would you recommend us to use an external service or analog line for that or should the 3cx be capable of processing these amount of fax messages.

 

[YiannisH_3CX]

When we disable the fallback option in the fax server and the other site doesn't support the t38 protocol the fax will fail correct ?

If the provider does not support T.38 and the option is off then the call will fail however QSC does support T.38 so you should be ok. I would recommend testing FAX with the option off and see if the issue persists. Also is this happening to all incoming FAX?
You could also create a ticket with our support department that can help you troubleshoot the issue.

 

[AWS2P]

HI,
Land line is the simplest and always working solution

 

[cobaltit]

For 80-100 faxes a day I would make my customer keep a POTS line or use my 'store-and-forward' fax service/adapter. FoIP is fine for low-volume, low page count, low priority faxes but if it matters, then see my previous recommendations. For example our main fax number is FoIP/T.38 but we get 3-4 faxes a month.