asterisk users - Dec 2005 - Analog terminals and modems? does it work

I have seen in several places where the analog adapters you can use for faxes
and modems have intermittent problems. Is this an issue with asterisk and are
there work-arounds?

We currently have side-stepped the issue by sharing the analog line between the
tdm card and the fax machine (I assume the tdm checks for dial-tone before
trying to assign the line.)  Long term, I am not so certain this is the idea
solution, so I was hoping for some experienced feedback.

Thanks,

I would recommend the new Sangoma analog card coming out over New Year.
It's built on the same quality standard and technical solution as the T1
cards.
You can mix and match FXO/FXS cards.

The other analog cards tends to have a lot of echo problems, but this
one seems a lot better.

To get fax detection working, the best (and sometimes the only) solution
is to use an analog card with the Zaptel driver. It automatically
adjusts to fax reception when it detects a fax tone.

Thanks
Bjorn 

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Chris
Gamble
Sent: Tuesday, December 20, 2005 9:17 PM
To: asterisk-users@lists.digium.com
Subject: [Asterisk-Users] Analog terminals and modems? does it work

I have seen in several places where the analog adapters you can use for
faxes and modems have intermittent problems. Is this an issue with
asterisk and are there work-arounds? 

We currently have side-stepped the issue by sharing the analog line
between the tdm card and the fax machine (I assume the tdm checks for
dial-tone before trying to assign the line.)  Long term, I am not so
certain this is the idea solution, so I was hoping for some experienced
feedback.

Thanks,
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> I have seen in several places where the analog adapters you can use for
faxes and
modems have intermittent problems. Is this an issue with asterisk and are there 
work-arounds? 
> 
> We currently have side-stepped the issue by sharing the analog line between
the tdm
card and the fax machine (I assume the tdm checks for dial-tone before trying to
assign
the line.)  Long term, I am not so certain this is the idea solution, so I was
hoping
for some experienced feedback.
> 
As has been noted several times, attempts to use modems over voip connections
will be less then reliable, incluidng the tdm card. Part of the reason is
the type of modulation used with some modems and part of it relates to 
tdm issues moving data across the pci bus (and/or interrupt latency).

The slower the modem, the more likely you can get something to work.

The tdm (and associated drivers) do not check for dialtone before dialing.