[Asterisk-Users] spandsp, rxfax, TDM400/zaptel, missed frames, any help?

[Philip Edelbrock]

Ben Fried wrote:
> On 1/9/06, Rich Adamson <radamson at routers.com> wrote:
> 
>>>Sorry in advance if this is a FAQ...
>>>
>>>I've got a working Asterisk setup based on A at H 2.2. I have a TDM400
>>>card with 2 FXS and 2 FXO ports; PSTN connections come in via the TDM
>>>card.
>>>
>>>I haven't been able to get inbound fax with spandsp and rxfax to work.
>>>Occasionally an all-text fax will come in, though it's usually badly
>>>corrupted, but in most cases, it would appear that the call is
>>>terminated without successful transmission of the fax. I get logs that
>>>look what's included below.
>>>
>>>>From reading the list, it looks like this is caused by the TDM card
>>>missing frames. Does that sound correct? If so, is there any relief in
>>>sight?
>>
>>Its been a problem since the card came out a couple of years ago. So, no
>>it does not appear there is any relief in sight.
> 
> 
> Sigh. What a disappointment! Are there any other options for home
> users to receive faxes over the PSTN through *? Is anyone working on
> an alternative to the zaptel driver that might fix this issue?
> 

Humm, I tried to get my TDM400 card accepting faxes last week.  It works 
about 1 out of 8 times.  When it works, it looks great.  When it 
doesn't, I usually (but not always) get a 'poor line quality' error from 
the sending fax machine and a blank or small corrupt image.

I've tried adjusting the gain up and down, reversing ring/tip, and a few 
other little things.  I wonder if it helps to adjust some other settings 
in the zapata.conf, like echo cancellation?

My hope is dwindling, though, after reading this thread. :'(  I do have 
a couple unused X100P clones sitting in that box that might be worth a 
try...


Phil