[Asterisk-Users] Re: Problems with TDM400P card

[Mike Mueller]

On Thu, May 05, 2005 at 08:46:45PM +0800, Steve Underwood wrote:
> Mike Mueller wrote:
> 
> >I am new to Asterisk, but so far, having looked at this thread (which is
> >quite long and full of lot's of hard work), the zttest code, the Digium 
> >web site,
> >and the spandsp website, and having talked to Digium sales/support about
> >the TDM, I think the issue belongs the spandsp community.  They may be
> >able to point out an improvement to the TDM product that Digium may or
> >may not implement.  Or they may need to adapt to an improvement on new TDM
> >cards. It does not appear that Digium has promised support to
> >the spandsp add-on function to Asterisk. I also didn't see where the 
> >spandsp
> >project was committed to staying up to date with each new revision of
> >TDM card - that's what the community is for.
> > 
> >
> Then you think wrong. This is totally unrelated to spandsp. 

Probably. I was careful to (CYA) point out my conclusion came only 
from what I learned in the recent discussions and research. 

> Any FAX 
> machine, modem, or other timing critical device has the same problems 
> with these cards.

I was hoping to learn if this was the case or not.  But are all or some fax/modems 
not working with recent TDM?

The system test becomes more complex now:

The benchmark becomes a wide selection of reputable fax/modems.  Pass 1
is TDM (including multiple revs of TDM, software and hosts) vs benchmark.
Pass 2 is spandsp vs benchmark. Pass 3 is TDM vs spandsp.

It's possible a pattern will emerge from Pass 1 that will obviate the
need for Pass 2/3.

> Something is broken, and since it used to work OK with 
> the hardware I am using now I assume it is the TDM driver.

TDM not working with fax/modems is a powerful indictment against TDM.

Also, if spandsp is reliable with spans and not TDM, yet another
indictment accrues against TDM.
> 
> By the way. Where is this spandsp community? I've never heard of them. :-)

Ouch :) Where's your P.C.?  Rich is a pretty strong advocate.  He was
using spandsp to slap TDM. I wasn't sure he could do that at first.  Now
I think its OK, but using modems and faxes to smack TDM will inflict
much more pain.

Lot's of users can be organized into a system test program the likes of
which no private concern can match.  This thread induced a spontaneous ad
hoc system test using zttest.  Pass 1 described above could be done as
follows:

1. Write up the test procedure.  The test cases are: 
   - line to line (3 cases: fxs/fxs, fxo/fxs, fxo/fxo)
   - line to span (2 cases: fxs/span, fxo/span)
   - line to IP (2 cases: fxs/IP, fxo/IP)
   for a total 7 conduit cases.  Running the test in two directions for each 
   conduit combination yields 14 possible test cases for each modem or fax. 
2. Specify how to report host, software, TDM, etc. configuration; write a script to
   compile the information.
3. Provide a wiki or something for test reports.

I've got FXO and FXS TDM on order, so I'll participate. 
-- 
Mike