asterisk users - Mar 2008 - PPP dialout via * server

I previously posted about this problem and received suggestions
involving turning off echo cancellation. As far as I can tell, echo
cancellation is already disabled on this channel, so I'm back.

What I've got is a small home setup with a single four-port Digium card:

Module 0: Installed -- AUTO FXS/DPO
Module 1: Installed -- AUTO FXS/DPO
Module 2: Installed -- AUTO FXS/DPO
Module 3: Installed -- AUTO FXO (FCC mode)
Found a Wildcard TDM: Wildcard TDM400P REV I (4 modules)

One outgoing Qwest line, three internal extensions. I also have a couple
of Snom SIP phones and X-lite soft phones on Mac, Linux, and Windows
boxes, and a VOIP line via Teliax, but the soft phones and VOIP line are
used only rarely. One of the internal extensions goes to a modem on a
Linux desktop. This desktop is able to send and receive faxes just fine.
If I have receive fax mode enabled on the desktop, then incoming faxes
are automatically routed to this box by Asterisk and it works great.
Outgoing faxes are also no problem.

The problem is that PPP dialout does not work; pppd eventually fails
with "NO CARRIER". Dialout works fine if I connect the modem straight
through to the wall plate, the problem only happens when the modem is
connected through Asterisk and the Digium card. The same modem and
connection through which faxing works fine. (For completeness, I also
tried the dialout via the Teliax line, but that didn't work either; I
didn't really expect that it would).

Here is my zaptel.conf file:

fxoks=1
fxoks=2
fxoks=3
fxsks=4
loadzone=us
defaultzone=us

Channel 4 is obviously the Qwest line, channel 1 is the desktop modem.

Here's zapata.conf:

[channels]
usecallerid=yes
hidecallerid=no
callwaiting=no
threewaycalling=yes
transfer=yes
echocancel=yes
echotraining=yes
immediate=no

; house phones
context=internal
signalling=fxo_ks
channel => 3
channel => 2

; infohigh fax modem
context=internal
signalling=fxo_ks
echocancel=no
echocancelwhenbridged=no
echotraining=no
threewaycalling=no
channel => 1

; Qworst line
context=incoming
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
rxgain=10.0
txgain=1.2
signalling=fxs_ks
faxdetect=incoming
channel => 4

Is there something else I need to do? Do I have to turn off echo
cancellation on the outbound line too? I don't think I really want to do
that all the time, or do I? If it only needs to be off when dialing out,
how do I accomplish that?

Thanks for any advice,

--Greg

Greg Woods wrote:
> The problem is that PPP dialout does not work; pppd eventually fails
> with "NO CARRIER". Dialout works fine if I connect the modem
straight
> through to the wall plate, the problem only happens when the modem is
> connected through Asterisk and the Digium card. The same modem and
> connection through which faxing works fine. (For completeness, I also
> tried the dialout via the Teliax line, but that didn't work either; I
> didn't really expect that it would).
Modem usage for data mode is quite substantially different that for FAX
mode; for one, FAX mode is always half-duplex transmission, which
drastically reduces the complexity of the audio signals. In addition,
data mode frequently wants to use bit rates of 14.4kbps (or higher)
where FAX is generally able to work well at 9.6kbps and lower.

In short, it is not likely that you will be able to accomplish what you
want using an analog interface card, and you may not be able to do it at
all, even using a digital interface card and a channel bank.

-- 
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)

I've been able to run low speed modems through a SIP ATA and an IAX 
trunk....bridged by asterisk.

I would assume that in this day and age any modem application through 
asterisk is probably for either a remote console or some sort of control 
system.  Either way using SIP and a very low speed should work for that 
type of stuff.

On Tue, 2008-03-04 at 12:05 -0600, Kevin P. Fleming
wrote:
> Greg Woods wrote:
> 
> > The problem is that PPP dialout does not work
                              From: 
Kevin P. Fleming
<kpfleming at digium.com>
>  it is not likely that you will be able to accomplish what you
> want using an analog interface card
OK, I bow to superior knowledge about how phone stuff works (of which I
have little). I can easily work around this by patching the modem around
the asterisk box on the rare occasions that I need to dial out. So this
was mostly a curiosity question, and I did learn something. Thank you.

--Greg