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Asterisk with modems instead of phonecards

 
 
acc admin
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      01-24-2005
Hello everyone,
I'm a newby

My company does not want to invest in FX0 cards for an office with two
phones. We already have some modems though.

Is it possible to setup Asterisk linux PBX with four modems (two for pstn
two lines, and two for inside phone cables going to phones), and then
through Asterisk make that work?

Or this could be even better if Asterisk server would have two modems
connecting to PSTN lines and act as a gateway for two IP phones via tcp/ip.

Thanks a Lot!


 
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BlueRinse
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      01-24-2005
> Is it possible to setup Asterisk linux PBX with four modems (two for pstn
> two lines, and two for inside phone cables going to phones), and then
> through Asterisk make that work?


The short answer is, no.
 
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Kyler Laird
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      01-24-2005
>> Is it possible to setup Asterisk linux PBX with four modems (two for pstn
>> two lines, and two for inside phone cables going to phones), and then
>> through Asterisk make that work?


>The short answer is, no.


The slightly longer and more correct answer is yes.

Make sure that you realize what "modem" means in this case. For connection
to the PSTN you'll need an "FXO" device and for connection to the telephones
you'll need "FXS" devices. There are more or less standard modems which
will do some of this. (I have used a Digium X100P modem with Asterisk.) I
recommend sticking with things that are designed to work with Asterisk.

The Digium product to do this all on one card is the TDM400P. (I have one.)
You'd then add two FXS and two FXO modules for a cost of over $300.
http://store.yahoo.com/asteriskpbx/tdtd2fxspo2f.html

I hate the sloppiness that results from connecting to a POTS line and I've
found my IP phones and Sipura devices to be much more satisfying so I don't
use Digium hardware anymore.

--kyler
 
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acc admin
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      01-24-2005
Thanks!

Ok, to simplify this, can i achieve the following:
Build an Asterisk Server with one SIP IP phone connected inside and an
outside phone line connected to a standard external modem, so that Asterisk
would be a PSTN gateway for that One phone?


"Kyler Laird" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> >> Is it possible to setup Asterisk linux PBX with four modems (two for

pstn
> >> two lines, and two for inside phone cables going to phones), and then
> >> through Asterisk make that work?

>
> >The short answer is, no.

>
> The slightly longer and more correct answer is yes.
>
> Make sure that you realize what "modem" means in this case. For

connection
> to the PSTN you'll need an "FXO" device and for connection to the

telephones
> you'll need "FXS" devices. There are more or less standard modems which
> will do some of this. (I have used a Digium X100P modem with Asterisk.)

I
> recommend sticking with things that are designed to work with Asterisk.
>
> The Digium product to do this all on one card is the TDM400P. (I have

one.)
> You'd then add two FXS and two FXO modules for a cost of over $300.
> http://store.yahoo.com/asteriskpbx/tdtd2fxspo2f.html
>
> I hate the sloppiness that results from connecting to a POTS line and I've
> found my IP phones and Sipura devices to be much more satisfying so I

don't
> use Digium hardware anymore.
>
> --kyler



 
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Kyler Laird
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      01-25-2005
"acc admin" <(E-Mail Removed)> writes:

>Build an Asterisk Server with one SIP IP phone connected inside and an
>outside phone line connected to a standard external modem, so that Asterisk
>would be a PSTN gateway for that One phone?


Again iff you use the right modem, sure, it's no problem. The X100P is one
such modem. At only $30 there's not much point in messing around with other
modems.
http://www.digitnetworks.com/store/p...4c951d57ba64f2

Also consider a Sipura SPA-3000. I suspect it'll do all that you want for
only $100.
http://store.voxilla.com/customer/pr...44&cat=0&page=

--kyler
 
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Miguel Cruz
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      01-25-2005
acc admin <(E-Mail Removed)> wrote:
> Ok, to simplify this, can i achieve the following:
> Build an Asterisk Server with one SIP IP phone connected inside and an
> outside phone line connected to a standard external modem, so that Asterisk
> would be a PSTN gateway for that One phone?


What do you mean by "standard external modem"? If you mean a 2400bps Hayes
MNP, then the answer is no. There are very few (if any) data modems that
provide satisfactory full-duplex voice operation. The chance that you will
happen to have one lying around without having bought it for that purpose is
quite low.

miguel
--
Hit The Road! Photos from 35 countries on 5 continents: http://travel.u.nu
 
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syd
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      01-25-2005
http://www.velocityreviews.com/forums/(E-Mail Removed) (Miguel Cruz) wrote in
news:(E-Mail Removed):

> acc admin <(E-Mail Removed)> wrote:
>> Ok, to simplify this, can i achieve the following:
>> Build an Asterisk Server with one SIP IP phone connected inside and
>> an outside phone line connected to a standard external modem, so that
>> Asterisk would be a PSTN gateway for that One phone?

>
> What do you mean by "standard external modem"? If you mean a 2400bps
> Hayes MNP, then the answer is no. There are very few (if any) data
> modems that provide satisfactory full-duplex voice operation. The
> chance that you will happen to have one lying around without having
> bought it for that purpose is quite low.
>
> miguel


Silly Questions #2

If i have a user with a analog modem can he dial out through *?

If I wanted to present myself as a dial up solution for low price, could i
purchase a "local" number in another area and have that user modem in to my
* and route that call to a computer on my network? I know my h.323 ATA is
really dsesigned to handle a fax machine, and that is a half duplex modem
for all intents and purposes.
 
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BlueRinse
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      01-25-2005
> Again iff you use the right modem, sure, it's no problem. The X100P is
> one such modem. At only $30 there's not much point in messing around with


I thought (hey I could have been wrong, but it appears I was not) by modem
he was saying any modem. This question comes up ten times a day in the
mailing list and on IRC and it almost always means "I have a modem [voice
modem, several modems] can I use this with *

The answer is, no.
 
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Miguel Cruz
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      01-25-2005
syd <syd_at_klassifiedbbs_dot_net> wrote:
> If i have a user with a analog modem can he dial out through *?


You don't need asterisk for that; just script it in your favorite language.

> If I wanted to present myself as a dial up solution for low price, could i
> purchase a "local" number in another area and have that user modem in to my
> * and route that call to a computer on my network?


I think you'll have trouble routing modem calls over VoIP links. Anyway,
it's a very inefficient way of doing things. Just make a deal with one of
the zillions of companies bulk-selling dialin services. You definitely can't
compete with them; their margins are tiny.

miguel
--
Hit The Road! Photos from 35 countries on 5 continents: http://travel.u.nu
 
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Doug McIntyre
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      01-26-2005
syd <syd_at_klassifiedbbs_dot_net> writes:
>Silly Questions #2


>If i have a user with a analog modem can he dial out through *?


Modems through VOIP links get at best around 9600-14400 baud
connections before they start crapping out using typical CODECs out there.

Obviously, you'd be restricted to 28800 speeds at best anyway, because
you'd be going through more than the one D/A conversion restriction
that makes 56k modems even work.

Seems like alot to go through just to get something like that.
 
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