Re: [hylafax-users] Help : MODEM <Empty Line>

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Anton Setiyono wrote:

> Jun 17 11:11:54.52: [30773]: <-- [10:AT+FRM=96\r]
> Jun 17 11:11:56.16: [30773]: --> [7:CONNECT]
> Jun 17 11:11:56.16: [30773]: RECV: begin page
> Jun 17 11:11:56.35: [30773]: RECV: 0 total lines, 0 bad lines, 1 consecutive bad lines
> Jun 17 11:11:56.35: [30773]: RECV: end page
> Jun 17 11:11:56.35: [30773]: --> [10:NO CARRIER]
> Jun 17 11:11:56.35: [30773]: <-- [9:AT+FRH=3\r]
> Jun 17 11:12:36.36: [30773]: --> [0:]
> Jun 17 11:12:36.36: [30773]: MODEM <Empty line>
> Jun 17 11:12:36.36: [30773]: <-- data [1]
> Jun 17 11:12:36.51: [30773]: --> [2:OK]

The translation of this portion of log is this...

At 11:54.52 the AT+FRM=96 command to detect and receive V.29 9600 bps 
modulated data was sent to the modem.  Less than two seconds later the 
modem reports CONNECT, which means that the V.29 9600 bps carrier was 
detected and that data reception would begin.  190 ms later the modem 
reports NO CARRIER, meaning that the modem detected a "drop" of the V.29 
9600 bps carrier (usually silence).

Following fax protocol HylaFAX then instructed the modem to detect and 
receive V.21 HDLC data with the AT+FRH=3 command.  However, after 
waiting 40 seconds the V.21 HDLC carrier was not detected, so the modem 
was instructed to "abort" the reception.

Realize that after 40 seconds with no interaction with the sender we're 
at a loss as to what to do next... so we just hang up in hopes that the 
caller will recall us... or in hopes that the caller hung up 
intentionally and knows what they're doing.

It's possible, however, that there was some error with the modem in that 
it may have erroniously detected V.29 carrier loss prematurely and that 
the ensuing V.29 modulated data portion lasted longer than 40 seconds.  
If this is the case then the modem may be at fault.  It's also possible 
that the *phone line* is at fault, especially if you (or the sender) are 
using VoIP "lines".

At this point the best way to determine where the fault lies is to make 
a recording of that call while it happens and to then analyze the audio 
data of that call piece-by-piece.  Unfortunately, you may not be able to 
do that.  So then the next-best thing to do is to try a different modem 
with a different chipset ... and if calls still fail like this with the 
different modem then it most likely indicates some problems with the 
phone lines in the connection.

Lee.


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