Asterisk with modems instead of phonecards

Archived from groups: comp.dcom.voice-over-ip (More info?)

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!
10 answers Last reply
More about asterisk modems phonecards
  1. Archived from groups: comp.dcom.voice-over-ip (More info?)

    > 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.
  2. Archived from groups: comp.dcom.voice-over-ip (More info?)

    >> 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
  3. Archived from groups: comp.dcom.voice-over-ip (More info?)

    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" <Kyler@news.Lairds.org> wrote in message
    news:6m2gc2-p55.ln1@lairds.us...
    > >> 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
  4. Archived from groups: comp.dcom.voice-over-ip (More info?)

    "acc admin" <cci-acc.admin@cciholdings.com.au> 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/product_info.php?products_id=28&osCsid=1299284a1df25dfed74c951d57ba64f2

    Also consider a Sipura SPA-3000. I suspect it'll do all that you want for
    only $100.
    http://store.voxilla.com/customer/product.php?productid=16144&cat=0&page=

    --kyler
  5. Archived from groups: comp.dcom.voice-over-ip (More info?)

    acc admin <cci-acc.admin@cciholdings.com.au> 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
  6. Archived from groups: comp.dcom.voice-over-ip (More info?)

    mnc@admin.u.nu (Miguel Cruz) wrote in
    news:jeKdnQEfsbYlamjcRVn-2A@speakeasy.net:

    > acc admin <cci-acc.admin@cciholdings.com.au> 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.
  7. Archived from groups: comp.dcom.voice-over-ip (More info?)

    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
  8. Archived from groups: comp.dcom.voice-over-ip (More info?)

    > 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.
  9. Archived from groups: comp.dcom.voice-over-ip (More info?)

    syd <syd_at_klassifiedbbs_dot_net> writes:

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

    Sure, analog modems can handle data fast enough for some voice calls.

    >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?

    You can use any (PPP/SLIP/...) IP connection to your Asterisk box for voice
    calls as long as the connection provides sufficient bandwidth for the codec
    you use and has latency you find satisfactory.

    --kyler
  10. Archived from groups: comp.dcom.voice-over-ip (More info?)

    "Miguel Cruz" <mnc@admin.u.nu> wrote in message
    news:jeKdnQEfsbYlamjcRVn-2A@speakeasy.net...
    > acc admin <cci-acc.admin@cciholdings.com.au> 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.

    There is a basic misunderstanding here. The cards that may act as FXO
    interfaces are so-called Winmodems (or Linmodems when used under Linux):
    devices where most of the encoding/decoding work when acting as modems is
    actually done by the CPU under the control of a device driver, and by a
    DSP also loaded with firmware by the device driver. Writing a suitable
    alternate device driver, one can give those cards a new lease of life as
    FXO interfaces towards POTS lines.

    Unfortunately, the characteristics of those cards vary from model to
    model, so there is no way of writing a universal driver for all the
    existing Winmodems. The Zaptel drivers for Asterisk include one (wcfxo.c)
    that works for two models: one, called by Digium X100P, based on a
    Motorola SM56 chipset (PCI ID: 0x1057, 0x5608); and another one, called by
    Digium X101P, based on an Intel chipset with TigerJet Network Tiger
    300/320 PCI interface (PCI ID: 0xE159, 0x0001). For any other Winmodem
    card, you are on your own...

    Enzo
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