[asterisk-users] faxing via linksys SPA3102 half page goes through

[Steve Underwood]

Marco Signorini wrote:
> Joseph wrote:
>   
>> On 03/04/09 15:44, Marco Signorini wrote:
>>   
>>     
>>> Hi Joseph.
>>> I've spent some time tuning the SPA3102 FXS line input and output gain
>>> and I think that this is an important variable.
>>> Let's try to record incoming and outgoing fax tones with asterisk on SIP
>>> channel (disabling the fax detection on SPA and sending fax inband) and
>>> look at the recorded file with a wave editor (Audacity).
>>> I had better results if the maximum level is near half to the full
>>> dynamic. Then switch to T38, if you need it.
>>>     
>>>       
>> As I remember I have experimented with gain on PSTN line as well but have reset back to default.
>> I have:
>> SPA To PSTN Gain:0
>> PSTN To SPA Gain:0
>>
>> I think "0"  is the default.
>>
>>   
>>     
> Yes, "0" is the default.
> Is the fax machine connected to the FXS port or do you use the SPA3102
> only as a SIP 2 PSTN gateway?
> If you use the FXS port, please take a look at the gain parameters you
> can find in the "Miscellaneous" section in the "Regional" page (log in
> as Administrator then switch to the "advanced" report).
>
> Now I've -5 as input gain and -2 as output. I don't know if this could
> helps you.
>
>   
I regularly do T.38 testing against and SPA3102, and they are quite 
troublesome. Different FAX machines and FAX modems give very different 
results. If you put a much longer lead between the FAX machine and the 
SPA3102 you may find it works a lot better. :-\

If you turn up the gains too much you get clipping, but as long as you 
don't go too far it shouldn't very sensitive.

Regards,
Steve