[hylafax-users] Failure to receive silence (synchronization failure)

[Anita Hall]

Hi

Sometimes, I am getting "MODEM No carrier", "MODEM Command error" followed
by "Failure to receive silence (synchronization failure)" for incoming Fax
over the PSTN. The E1 line is connected to PC running FreeSWITCH which
provides a soft modem via mod_spandsp.

For such failures, the logs are of different sizes corresponding to
different call durations. The call durations vary from 6 seconds to more
than 40 seconds in some cases.

How to debug more to reduce such errors or find their main cause ?

Here is one of the longer logs

# cat log/c000000089
Jul 17 18:55:45.09: [28414]: SESSION BEGIN 000000089 19995551212
Jul 17 18:55:45.09: [28414]: HylaFAX (tm) Version 6.0.5
Jul 17 18:55:45.09: [28414]: CallID: "1614637232"
"a//srv/sounds/fax/e71aaa1a-d012-11e1-b8f1-398cb2486692.tiff"
Jul 17 18:55:45.09: [28414]: <-- [4:ATA\r]
Jul 17 18:55:49.23: [28414]: --> [7:CONNECT]
Jul 17 18:55:49.23: [28414]: ANSWER: FAX CONNECTION DEVICE '/dev/FS0'
Jul 17 18:55:49.23: [28414]: RECV FAX: begin
Jul 17 18:55:49.24: [28414]: <-- data [32]
Jul 17 18:55:49.24: [28414]: <-- data [2]
Jul 17 18:55:50.19: [28414]: --> [7:CONNECT]
Jul 17 18:55:50.19: [28414]: <-- data [23]
Jul 17 18:55:50.19: [28414]: <-- data [2]
Jul 17 18:55:50.93: [28414]: --> [7:CONNECT]
Jul 17 18:55:50.93: [28414]: <-- data [13]
Jul 17 18:55:50.93: [28414]: <-- data [2]
Jul 17 18:55:51.53: [28414]: --> [2:OK]
Jul 17 18:55:51.53: [28414]: <-- [9:AT+FRH=3\r]
Jul 17 18:55:58.53: [28414]: --> [0:]
Jul 17 18:55:58.53: [28414]: MODEM <Empty line>
Jul 17 18:55:58.53: [28414]: <-- data [1]
Jul 17 18:55:58.55: [28414]: --> [2:OK]
Jul 17 18:55:58.55: [28414]: <-- [9:AT+FRS=7\r]
Jul 17 18:55:58.58: [28414]: --> [2:OK]
Jul 17 18:55:58.58: [28414]: <-- [9:AT+FTH=3\r]
Jul 17 18:55:58.60: [28414]: --> [7:CONNECT]
Jul 17 18:55:58.60: [28414]: <-- data [32]
Jul 17 18:55:58.60: [28414]: <-- data [2]
Jul 17 18:56:00.37: [28414]: --> [7:CONNECT]
Jul 17 18:56:00.37: [28414]: <-- data [23]
Jul 17 18:56:00.37: [28414]: <-- data [2]
Jul 17 18:56:01.11: [28414]: --> [7:CONNECT]
Jul 17 18:56:01.11: [28414]: <-- data [13]
Jul 17 18:56:01.11: [28414]: <-- data [2]
Jul 17 18:56:01.69: [28414]: --> [2:OK]
Jul 17 18:56:01.69: [28414]: <-- [9:AT+FRH=3\r]
Jul 17 18:56:08.69: [28414]: --> [0:]
Jul 17 18:56:08.69: [28414]: MODEM <Empty line>
Jul 17 18:56:08.69: [28414]: <-- data [1]
Jul 17 18:56:08.71: [28414]: --> [2:OK]
Jul 17 18:56:08.71: [28414]: <-- [9:AT+FRS=7\r]
Jul 17 18:56:08.74: [28414]: --> [2:OK]
Jul 17 18:56:08.74: [28414]: <-- [9:AT+FTH=3\r]
Jul 17 18:56:08.75: [28414]: --> [7:CONNECT]
Jul 17 18:56:08.76: [28414]: <-- data [32]
Jul 17 18:56:08.76: [28414]: <-- data [2]
Jul 17 18:56:10.53: [28414]: --> [7:CONNECT]
Jul 17 18:56:10.53: [28414]: <-- data [23]
Jul 17 18:56:10.53: [28414]: <-- data [2]
Jul 17 18:56:11.27: [28414]: --> [7:CONNECT]
Jul 17 18:56:11.27: [28414]: <-- data [13]
Jul 17 18:56:11.27: [28414]: <-- data [2]
Jul 17 18:56:11.85: [28414]: --> [2:OK]
Jul 17 18:56:11.85: [28414]: <-- [9:AT+FRH=3\r]
Jul 17 18:56:18.85: [28414]: --> [0:]
Jul 17 18:56:18.85: [28414]: MODEM <Empty line>
Jul 17 18:56:18.85: [28414]: <-- data [1]
Jul 17 18:56:18.87: [28414]: --> [2:OK]
Jul 17 18:56:18.87: [28414]: <-- [9:AT+FRS=7\r]
Jul 17 18:56:18.90: [28414]: --> [2:OK]
Jul 17 18:56:18.90: [28414]: <-- [9:AT+FTH=3\r]
Jul 17 18:56:18.91: [28414]: --> [7:CONNECT]
Jul 17 18:56:18.91: [28414]: <-- data [32]
Jul 17 18:56:18.91: [28414]: <-- data [2]
Jul 17 18:56:20.69: [28414]: --> [7:CONNECT]
Jul 17 18:56:20.69: [28414]: <-- data [23]
Jul 17 18:56:20.69: [28414]: <-- data [2]
Jul 17 18:56:20.81: [28414]: --> [10:NO CARRIER]
Jul 17 18:56:20.81: [28414]: MODEM No carrier
Jul 17 18:56:20.81: [28414]: <-- [9:AT+FRS=7\r]
Jul 17 18:56:20.82: [28414]: --> [5:ERROR]
Jul 17 18:56:20.83: [28414]: MODEM Command error
Jul 17 18:56:20.83: [28414]: Failure to receive silence (synchronization
failure).
Jul 17 18:56:20.83: [28414]: RECV FAX: Failure to receive silence
(synchronization failure).
Jul 17 18:56:20.83: [28414]: RECV FAX: end
Jul 17 18:56:20.83: [28414]: Failure to receive silence (synchronization
failure).
Jul 17 18:56:20.83: [28414]: SESSION END

The config is

#cat etc/config.FS0

CountryCode: 1
AreaCode: 124
FAXNumber: +1.999.555.1212
LongDistancePrefix: 1
InternationalPrefix: 011
DialStringRules: etc/dialrules
ServerTracing: 1
SessionTracing: 11
RecvFileMode: 0777
LogFileMode: 0777
DeviceMode: 0777
RingsBeforeAnswer: 2
SpeakerVolume: off
GettyArgs: "-h %l dx_%s"
LocalIdentifier: "NothingSetup"
TagLineFont: etc/lutRS18.pcf
TagLineFormat: "From %%l|%c|Page %%P of %%T"
MaxRecvPages: 25
ModemType: Class1 # use this to supply a hint
Class1Cmd: AT+FCLASS=1.0 # command to enter class 1.0
Class1PPMWaitCmd: AT+FTS=7 # command to stop and wait before
PPM
Class1TCFWaitCmd: AT+FTS=7 # command to stop and wait before
TCF
Class1EOPWaitCmd: AT+FTS=9 # command to stop and wait before
EOP
Class1SwitchingCmd: AT+FRS=7 # command to stop and listen for
silence
Class1RecvAbortOK: 200 # wait 200ms for abort response
Class1FrameOverhead: 4 # 4 byte overhead in recvd HDLC
frames
Class1RecvIdentTimer: 40000 # 35+5secs waiting for ident frames
Class1TCFMaxNonZero: 10 # max 10% of data may be non-zero
Class1TCFMinRun: 1000 # min run is 2/3rds of TCF duration
ModemResetCmds: AT+VCID=1
CallIDPattern: "NMBR="
CallIDPattern: "NDID="



regards,
Anita

[Lee Howard]

On 07/17/2012 08:52 AM, Anita Hall wrote:
> Sometimes, I am getting "MODEM No carrier", "MODEM Command error"
> followed by "Failure to receive silence (synchronization failure)" for
> incoming Fax over the PSTN. The E1 line is connected to PC running
> FreeSWITCH which provides a soft modem via mod_spandsp.
>
> For such failures, the logs are of different sizes corresponding to
> different call durations. The call durations vary from 6 seconds to
> more than 40 seconds in some cases.
>
> How to debug more to reduce such errors or find their main cause ?

In the case that you provided where there is never any V.21 HDLC
detection as reported by AT+FRH=3...

> Jul 17 18:55:51.53: [28414]: <-- [9:AT+FRH=3\r]
> Jul 17 18:55:58.53: [28414]: --> [0:]
> Jul 17 18:55:58.53: [28414]: MODEM <Empty line>
> Jul 17 18:55:58.53: [28414]: <-- data [1]
> Jul 17 18:55:58.55: [28414]: --> [2:OK]

.. you'll need to record the audio of the call and listen to it to
confirm the modem's claim that there is no fax audio on the call or that
the fax audio is too corrupted to be useful. Assuming the modem is
correct, then you need to look upstream on the call somewhere:
FreeSWITCH, the E1, the telco, the sender. If the modem is incorrect,
then it's an issue to report to the soft-modem developers.

Thanks,

Lee.


____________________ HylaFAX(tm) Users Mailing List _______________________
To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-bin/lsg2.cgi
On UNIX: mail -s unsubscribe hylafax-us...@hylafax.org < /dev/null
*To learn about commercial HylaFAX(tm) support, mail sa...@ifax.com.*