[Asterisk-Users] FXS or VOIP

[Colin Anderson]

>What about fax machines working over a PRI T1
>line?  Run FXS ports to each fax machine and the
>TDM card will convert the digital T1 to analog
>for faxing?

>I have no POTS lines, just a T1 (PRI soon if I
>find out I can use asterisk for regular POTS-type
>faxing).

I tried that and wasn't happy with the results (TE110 -> TDM400). There's
some frame slippage involved as soon as you hit the PCI bus that's enough to
make faxing unstable (your box might fare better tho). It's small, but
enough to cause problems.  In my dialplan, I use spandsp to rx the fax, and
I have an "exception list" of known fax machines that have a problem tying
up to spandsp, and if an inbound fax machine's callerid = an entry on the
list, Asterisk forwards the call to a regular fax plugged into an Adtran
channel bank. Works Good. 50K+ faxes from May to Dec 31,05 with only a 1%
failure rate. 

I maintain the exception list by having a script that examines the generated
PDF after fax RX, and if it's less than 46 bytes, it's a bad fax, and it
emails me / SMS's me about it. That way, as soon as a bad fax comes in I
know about it, and sometimes I can be fast enough to update the exception
list between retries, so the remote fax doesn't generate an error for the
sender.


---- Begin Original Message ----

From: "Wiley Siler" <wsiler at education2020.com>
Sent: Wed, 11 Jan 2006 15:20:03 -0700
To: "Asterisk Users Mailing List - Non-Commercial
Discussion"<asterisk-users at lists.digium.com>
Subject: RE: [Asterisk-Users] FXS or VOIP


I think what he means is that an * server can
support hundreds of phones
because the server connects to the network via a NIC.
Port count becomes irrelevant when you thing
about VoIP phones
connecting to a VoIP server.  They connect over
the network not point to
point.
It is just a matter of bandwidth and network
topography at that point.

If your desire it to connect a bunch of analog
phones then you can use
ATAs.
I would recommend that you just replace them though.

You should only need to worry about your POTS
lines at this point.
If you have 4 POTS lines, a single 4 port TDM
card will suffice.

Cheers,
W


 

-----Original Message-----
 From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com]
On Behalf Of Jim Freeze
Sent: Wednesday, January 11, 2006 2:57 PM
To: Asterisk Users Mailing List - Non-Commercial
Discussion
Subject: Re: [Asterisk-Users] FXS or VOIP

On 1/11/06, William Boehlke
<william.boehlke at signate.com> wrote:
>
> A single computer will handle hundreds of
telephones. Just get a card 
> with more ports, or use an external gateway.

I am sorry, I don't understand. Are you talking
about analog FXS phones?
All the PCI cards I have seen have a max of 4 FXS
lines and the external
boxes seem very expensive.

--
Jim Freeze
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