Modem -> VoIP line -> modem?

Discussion in 'UK VOIP' started by Pacman, Feb 18, 2008.

  1. Pacman

    Pacman Guest

    Maybe its a basic question. But I am trying to find out:

    Is it possible to dial in using a modem to another Computer behind an "VoIP
    only" connection?

    Szenario: home user with an internet contract that provides DSL. The phone
    line bundled with the contract is established as VoIP. So no "real" land
    line phone.

    Is it now possible to create a classic dial in to a server?

    Extension: would it be possible to do a classic modem-modem call back as

    (all this at low cost - no cisco routers or something)

    I found some words like modem relay but I am not sure to be on the right

    Pacman, Feb 18, 2008
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  2. Pacman

    Ivor Jones Guest

    : : Maybe its a basic question. But I am trying to find out:
    : :
    : : Is it possible to dial in using a modem to another
    : : Computer behind an "VoIP only" connection?
    : :
    : : Szenario: home user with an internet contract that
    : : provides DSL. The phone line bundled with the contract
    : : is established as VoIP. So no "real" land line phone.

    Not possible. You have to have a landline in order to get DSL.

    Ivor Jones, Feb 19, 2008
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  3. Pacman

    Jono Guest

    Ivor Jones formulated the question :
    Not true for everywhere.

    Nor is it necessarily completely true in this country - you can
    certainly have ADSL on a line that is provisioned with OCB & ICB.
    Jono, Feb 19, 2008
  4. Pacman

    mr deo Guest

    I think he is just asking if VoIP can let him use a POTS modem for end->end
    From what I know of VoIP the answer is no, but I am sure something he wants
    does exist (just see no reason why he would want it)
    mr deo, Feb 19, 2008
  5. Pacman

    Paul Hayes Guest

    Maybe I'm reading this wrong but why on earth would you want to attempt
    a modem connection using VoIP when the VoIP is already going to be on a
    broadband connection anyway?

    Anyway, the answer is you might be able to get a *very* slow modem
    connection working (14.4kbps at the most using normal g711 codecs) but
    even then it's likely to be unreliable. You'd also need to buy an ATA
    to connect the modem to if you don't already have one, although perhaps
    you already have a router with an ATA built-in since you've got VoIP
    with your Internet connection already.

    Paul Hayes, Feb 19, 2008
  6. When you want to connect to a server that isn't on the Internet. Like
    dialling into a remote datalogger, a burglar alarm or something.
    Would T38 fax support be any help here? Does it do anything special
    regarding faxes, or is it just a way of reliably sending 9600 or 14400 bps
    traffic over VOIP?

    Theo Markettos, Feb 19, 2008
  7. Pacman

    Desk Rabbit Guest

    Setting aside what you think is the solution to your problem, what is it
    you are actually trying to achieve?
    Desk Rabbit, Feb 19, 2008
  8. Pacman

    Pacman Guest

    Some more detail about the szenario:

    yes, it is a DSL without land line (Germany).

    plan is to connect a remote place to the internet. the remote place can not
    have dsl. so the only way is to connect via analog or isdn. being online
    would cause online minutes to be paid.

    so the thought is to diel from the remote computer (modem) to a location
    where dsl is available. get a recall triggered and connect from the
    dsl-location to the remote place. (the dsl-location has a telephone flat
    contract so no pay per minute needed)
    then the dsl-place acts as an ISP routeng web traffic.

    maybe that is a slow connection. would not be that bad - main thing is being
    online for free. would using isdn change anything?

    Pacman, Feb 19, 2008
  9. Pacman

    Tim Guest

    Fax specific.

    Tim, Feb 19, 2008
  10. Pacman

    Tim Guest

    He's trying to be his own ISP to somewhere that can't have DSL.

    Tim, Feb 19, 2008
  11. Pacman

    Pacman Guest

    yes, thats what it looks like...
    Pacman, Feb 22, 2008
  12. Pacman

    tc Guest

    I'm trying to do something similar and am struggling !

    I have a bunch of dataloggers at remote locations with gsm modems. On
    the PC at base I have standard analogue modem on a BT line, which I
    use to download data and manage the loggers. I want to discard the BT
    line and to see if I can do this operation via VOIP or another
    internet based process. Download speed only needs to be 9600 (the max
    speed for the GSM modems).

    There are useful articles on the principles at
    & over VOIP but
    I have no found any info on a practical "how to" solution. The
    problems seem to be to do with the compression codecs used in VOIP
    being designed for voice and not data - surely there is a software
    solution somewhere ???

    Any ideas/help would be appreciated
    tc, Mar 8, 2008
  13. If you can use VoIP, them you have broadband... If you have broadband
    then you either have cable or ADSL, and if you have ADSL, then you need
    a phone line - which you can use for a modem...

    I'll assume you have cable and you want to save money by dropping the BT

    Modem and FAX data don't work well over VoIP because, while we humans
    can ignore then odd click, packet loss, or duplication, a modem can't.
    On top of that is the digitization of the signal - and if you compress
    it with a lossy compression, then you can not reconstruct enough of the
    modem signal at the other end to reconstruct the data stream. (Even if
    the modem can actually recognise the resulting compressed noise!)

    So far better to keep the PC at base with it's standard BT line and
    modem to collect data from the remote sites - put ADSL on the BT line,
    and use that to send the decoded data to other sites, as required.

    How much data are we talking about here? If it's < 160 bytes at a time,
    then why not send it as a TXT message? You could then have a GSM modem
    on the PC, and from there send the data out via broadband (Cable,
    I assume, since if you wanted ADSL, you'd have the phone line)

    You could just try it and you might get away with it... Get an ATA
    and a VoIP account with a geographic number - make sure the ATA is fixed
    to use G711a and connect a modem to the ATA and see what happens ...

    If you want to eliminate cables, get a VoIP provider that can give you
    an IAX feed and get IAXMODEM -

    Your PC will need to be running Linux though.

    Another way might be to get someone to run the "modem" for you at the
    end of their VoIP connect - if they have a better than ADSL/Cable
    quality connection... Then get that site to post the data to your
    processing PC via the Internet... (Or have it processes at a remote site
    doing this for you). However I'm guessing that as you want to dump the
    BT line to presumably save £11 a month, you're doing this really on the
    cheap, so who knows if you'll get anyone to let you do this who might
    charge you less than £11 a month. (But if this is an option, drop me an

    Gordon Henderson, Mar 8, 2008
  14. Pacman

    tc Guest

    Thanks for that Gordon - So it may be just possible in principle, but
    it is unlikely to be that good. This is more or less what i gathered
    reading around the subject, but v helpful to have it explained so

    I'm binning BT anyway, so I better just get another dedicated fax/
    modem line with the new supplier. The risk of data loss is way more
    than £11 pm !

    tc, Mar 9, 2008
  15. Pacman

    Tim Guest

    Why don't you use a GSM modem at the local end?

    Old Nokia phone + cable.

    I think you will get faster initialization times on calls with it being
    GSM to GSM.


    Other long term option would be to swap to dataloggers using GPRS. Then
    they can be always online sending info to you over the internet. I know
    a company that does a lot of work in this area.

    Tim, Mar 11, 2008
  16. Pacman

    Nov 25, 2013
    Likes Received:
    Answer on your voip problem

    If I understand it correct you would like to have two different destinations with both adsl connections dial over a voip connection to each other and have it work. If this is the case pls let me know couse I do have an answer
    , Nov 25, 2013
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