[Asterisk-Users] Major problems with TDM400 and specific telephones: suggestions?

[tmassey at obscorp.com]

Hello!

Attached to the bottom of this e-mail is an edited version of an e-mail I 
originally wrote to Digium tech support regarding Ouch and Power alarm 
errors I have been receiving on my TDM400.  It contains a great deal of 
detail regarding my setup.  In the end, I have found that one of the 5 
phones I'm trying to make work with Asterisk is contributing to the 
generation of these errors.

The phone in question is what I would consider to be a good-quality GE 
two-line cordless telephone.  Digium's guess is that it is "putting power 
on the telephone line and the card doesn't like that."  They have given me 
zero solution other than to use a different telephone.

If this were a $25 garbage telephone I could understand.  Or, if *any* 
other device had problems with it, I could understand.  But this was a 
reasonably expensive, seemingly reasonably high quality telephone.  It is 
also a telephone that I have used quite successfully not only on standard 
POTS lines, but also on a variety of ISDN NT-1's with zero problems.  I 
don't mean that I've used this model.  I've used this *phone* on at least 
4 different brands and models of NT-1's, several different POTS lines and 
even an SPA-2000.  Not one bit of problem.  Yet the TDM400 card just 
chokes itself with Power alarm and Ouch errors.

Does anyone have any idea of what I can do to try to correct this?  Is 
there some sort of filter or adapter that I can use to condition the line 
for the TDM400 FXS modules?  I'm handy with a soldering iron:  if you've 
got an idea for a circuit, I'm game.  I'm going to try experimenting with 
some caps and coils.  Anyone been down this road yet?

As an aside, why is it that just about *any* other device with an analog 
interface you can buy today more robust than the TDM cards?  I've used 
countless different ISDN NT-1's without problems, from $100 cheapo models 
to $1000 high-end devices and tons in between and none have had problems 
like this.  Now there's a ton of SIP gateway devices.  They don't seem to 
have these issues.  Why do the TDM cards?  And most importantly, can an 
end user do anything about this?

Tim Massey





Hello!

I have been struggling to get a TDM400 card working for some time now.  I 
have a TDM400 with 3 FXS modules and 1 FXO module.  Right now, the FXO is 
installed but not connected to anything, and the FXS are connected to a 
number of telephones, including an inexpensive Lucent standalone analog 
phone, a 2-line AT&T standalone analog phone, a 2-line GE analog 
speakerphone with AC adapter, an inexpensive VTech cordless telephone with 
AC adapter, and a 2-line GE cordless phone, also with AC adapter.  I am 
testing the board right now just by calling back and forth internally from 
extension to extension.

As long as I do not have the GE cordless phone plugged in, there seems to 
be no problems so far.  At least, I do not believe I have yet seen the 
problem when the GE is not plugged in.  Also, if I do not pick up the GE 
cordless phone, I do not get any errors.  However, if I take the GE 
cordless phone off hook or put the phone back on hook, I will get "Ouch, 
part reset, quickly restoring reality (#)" errors, as well as "Power alarm 
on module #, resetting!" errors.  This does not happen every time I pick 
up or hang up the phone, but after a relatively short number of times 
(say, under 20 at the very most) I will get one or both of the errors.

It seems that the "Ouch" errors are indexed from zero, and the "Power 
alarm" errors are indexed from one.  The port that generates these errors 
seems to vary.  While the port that the GE cordless phone is plugged into 
seems to appear a decent amount, it is far from consistent.  For example, 
right now the cordless phone is in port 1.  However, I've gotten two Ouch 
errors, one for 0 and one for 1, and I've gotten three Power alarm errors, 
two for module 2 and one for module 1.

After an error, channels on the the board often become very staticy.  I 
believe that this only happens after a Power alarm, not after an Ouch 
error.  In fact, I am pretty (but not completely) sure that after an Ouch 
error the board (or at least individual channels that are reset) clears 
up.  Also, not just the channel that have had an error is affected: 
sometimes (but not always) all of the channels are affected.  Sometimes 
the dialtone can be heard through the static, sometimes not.  Even when 
the dialtone can be heard, it does not respond to DTMF tones.  This varies 
from channel to channel:  for example, right now, the dialtone can be 
heard through the static on one channel, but the other two have louder 
static, and I cannot hear a dialtone.  I don't think the static is 
drowning out the dialtone:  I think it's plain not there.  Also, if I 
leave those channels off hook, I do not get a busy signal.  Or at least, I 
don't hear a busy signal...

Exiting Asterisk does not affect this.  The static stays the same.  Of 
course, with Asterisk exited, there is no dialtone on any channel, but the 
static remains.  Restarting Asterisk causes the dialtone to return on 
those channels that had dialtone before, but the static remains.

Bouncing the wctdm driver *does*, however, restore operation to all 
channels, at least for a little while.

Until the error occurs a single time, I can call back and forth from 
device to device (including the GE cordless) for a while without problems. 
 However, once I get a single error, I tend to get lots of errors from 
then on out until the driver is bounced.  I can get these errors by doing 
nearly anything:  picking up any phone, dialing any phone, etc.  I 
certainly do not get an error every time I do anything, but nearly any 
action has the potential for causing an error.  Also, while I believe that 
the "Ouch" errors restore the board (or at least, individual channels) to 
a working state, it does not prevent the error from happening again: 
unlike bouncing the driver the errors continue to happen quickly even 
after an "Ouch".

The GE cordless telephone is not a cheap quality (or even, for that 
matter, inexpensive) cordless telephone.  It is described as a 
business-class telephone.  It is a phone that I have used successfully 
with normal POTS lines, a number of ISDN NT-1's, and other such devices. I 
have had zero problems with it in any other case:  in fact, it's the best 
cordless phone I've ever used!  :)  I do not know why this phone should 
cause a problem with the TDM card when it does not cause a problem for 
anything else.

What about this phone could be causing this problem?  More importantly, 
what can be done to correct this?  I have loaded the driver with the 
lowpower=1 parameter, the robust=1 parameter and even both at the same 
time.  This has had no effect.  What else can I do?  I have tried plugging 
the GE cordless into each of the three FXS modules I have and I get 
problems with each of them.  I have also tried two radically different 
systems:  a Via EPIA-MII single-board computer, and an IBM Netfinity 5600 
file server.  I don't know how you can get two more different systems, yet 
both systems give me the same problems.

<Conact information and polite conclusion snipped>

Thank you,

Timothy J. Massey