FoIP through Lingo

Discussion in 'VOIP' started by DanG, Apr 3, 2005.

  1. DanG

    DanG Guest

    Hi all,

    I need to be able to send and receive faxes at home. I recently
    switched from dial-up to VoIP (Lingo) because they said they supported
    faxing. Of course, now, my PC software (WinFax) doesn't work. I
    called up Lingo tech support, who said faxing will only work to/from a
    fax machine, not a PC. Also, they only support any protocol EXCEPT

    I've been reading up about T.37 and T.38, but I'm still looking for a
    straight answer. I understand that T.38 will not work, but that T.37
    might. I don't understand why a fax machine would work, when a PC
    won't. Seems that a fax machine is only running software, so why
    couldn't a PC do it?

    Anyway, before I run out and buy a fax machine, I wanted to get y'all's
    opinions. Do I really need a fax machine? If so, is there anything I
    need to look for in the way of supported protocols? I'd really prefer
    to send/receive the documents digitally. Is there really no PC
    software that will work? (Not server stuff -- just something free or
    relatively cheap.) I've seen some software that seems to allow sending
    faxes via T.37, but not receiving.

    I'm running WinXP. Cable -> Router -> Lingo box -> phone line -> PC
    (fax modem).

    Any suggestions are welcome.

    DanG, Apr 3, 2005
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  2. DanG

    Pepperoni Guest

    Legally, a fax machine must be tied to a phone number. That number is
    transmitted with the fax. (or so it was explained to me)

    Check out EFax.
    You can receive faxes using the free program, but need the paid version to

    " Your risk-free trial allows you to receive faxes at up to 5 different
    email addresses and send up to 50 fax pages. After 30 days, regular eFax
    rates will apply."

    You may be able to use a virtual desktop into your office and send through
    your office fax machine.

    Pepperoni, Apr 3, 2005
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  3. DanG

    DanG Guest

    My home phone system uses a phone number (the one folks use to call
    me), and my PC modem is connected to that phone system. Doesn't that
    answer any legal questions? You know, the WinFax software recognizes
    that a call is coming in, and the caller ID even works. Sometimes I
    even get partial pages of incoming faxes. If it's just a protocol
    issue, I'd think some software would be smart enough to hande it.

    As far as a monthly service, was cheaper than eFax. It's
    $10/mo, and includes 100 sent pages and 200 received pages. However, I
    don't need a LOT of faxes in or out. I may even go months without
    using it. But I do need to do it on occasion. I didn't want to pay a
    montly fee for something I don't need every month. I may have to do it
    though, until technology catches up with the need.

    Any other voices out there?


    On a clear disk, you can seek forever.
    DanG, Apr 3, 2005
  4. DanG

    Pepperoni Guest

    Fax is sometimes twitchy. There may be a hardware solution. I figure trying
    to run a PC on the same connection may be the cause of the problem. Most
    folks run a dedicated fax line and still have problems. If I really needed
    a document, I'd rather receive a TIFF file by email, anyway.
    Pepperoni, Apr 3, 2005
  5. I've used the efax system with SunRocket and have had a pretty good
    experience with it. Overall, both efax and SunRocket seem to work well
    together. I would imagine efax would work well all around.
    ukcats4218016, Apr 4, 2005
  6. The reason that Lingo only officially supports fax machines rather than
    PC-based fax solutions might have to do with the fact that Win-modems are
    notorious for not adhering to the standards that govern modems and fax
    machines. (I assume that your fax solution on your PC is a program running
    on top of an internal or external modem (a "Win-modem".) Most Win-modems
    are designed and manufactured as cheap and dirty as can be pushed out the
    door - as fast as possible. So, their performance is typically awful, and
    they break the tight timing requirements of the T.30 standard, which governs
    the communications between two fax entities. That said, there is no
    functional difference between a regular fax machine and a PC-based fax
    solution that has a modem with come sort of communications software running
    in top of it. I mean, they both have a 2-wire interface to the telephony
    line, right - so how would Lingo's gateways even know what you're running?
    The fact it, they don't, at least until the initial handshake sequence is

    What is your exact setup, BTW?
    Do you mean that they support ANY protocol EXCEPT T.38 (i.e. AAL2 or FRF.11
    fax relay)? Or they ONLY support T.38? I suspect the latter, since you're
    almost certainly in an IP-based environment. No problem - T.38 is robust
    and it works.
    T.37 is store-and-forward fax over an IP network. T.38 is real-time fax
    over an IP network. Find out for sure from your provider which (if not
    both) they support.
    Now I'm confused. You mentioned earlier that you "recently switched from
    dial-up to VoIP (Lingo)..." Does this mean that you switched from a dialup
    connection to broadband for your PC's internet access? If so, then we're
    dealing with a different kettle of fish. Let's get an exact idea of your
    setup before we move on.

    James Calivar, Apr 4, 2005
  7. DanG

    DanG Guest

    I use CableOne through the cable box to a LinkSys router, into the
    Lingo box. The Phone 1 port's line runs into the homerun, where the
    phone lines are sent out to the jacks around the house. One of those
    jacks has a phone line into the modem on the PC. The PC is running
    WinFax, but Microsoft Fax didn't work either. Is there anything I've

    The techie did say they support any protocol EXCEPT T.38. Since I
    didn't know anything about protocols at the time, I asked him to
    confirm, which he did. He also said that any fax machine should work,
    as long as it doesn't run T.38.

    But then, I had other troubles with Lingo (dropped calls, no dial tone,
    etc.), and I had to talk to four different techies before I found one
    that really knew how to fix the problem. Maybe the guy I talked to
    about faxing didn't know about FoIP, either. (shrug)

    DanG, Apr 4, 2005
  8. Hmm. I think I might see the problem. (Bear in mind that I could be wrong
    here.) If you've transitioned your PC's internet access from dialup (using
    a modem) to cable access, that means that you've by necessity had to
    reconfigure your PC's network settings. Chances are good that the modem is
    now disabled, since it's no longer your conduit into your ISP. All your
    PC's packet network traffic is now going out through an Ethernet adapter,
    into your cable modem router, then out to the cable connection, instead of
    through the modem like it used to. So, you may not be able to use the PC as
    a fax machine, because the fax software on your PC communicates with the
    modem, and uses it to do actual modulation/demodulation of the fax traffic.
    Since the modem is now "out of the loop" as far as your ISP is concerned,
    the fax data has nowhere to go. Now, I'm no expert on cable modem
    technology, and I don't know your exact network topology, but unless you've
    connected up the PC's modem to a 2-wire RJ-11 jack on your cable modem box,
    you're not going to get anywhere. (I think you said before that you had
    connected the modem to a phone jack on the cable modem box, right?) Even if
    you have, it may be that the modem has been disabled internally through some
    settings in your PC's network configuration. The real way to test this is
    to try to make a fax call using your PC and the modem through a regular
    phone line to see if your PC is still capable of sending faxes. If it
    isn't, then something has changed on your PC and you need to fogure out how
    to re-enable it. If it is, then clearly the problem now resides with the
    fact that your phone service is now running through the cable modem box.
    So what the techie is saying is that their media gateways (up at the ISP's
    head end) do not support T.38 fax relay. This is quite typical of cable
    providers - they look for the cheapest solution, and that solution is
    typically so-called "fax passthrough", where the fax traffic goes through
    the G.711 64kbps PCM voice codec, instead of being sent to a T.38-capable
    fax relay codec. All this means to the layperson is that you can't expect
    to use an IAF ("Internet Aware Fax") device to send faxes; rather, you must
    use a standard T.30-compliant Group 3 fax device (such as a regular old fax
    machine, or a PC running a fax-capable modem) in order to send faxes. This
    is not an issue here since you're not trying to employ an IAF.
    We can find a fix to this problem. The dropped calls and no dialtone
    situations you listed don't give me a lot of confidence in your ISP, so we
    might end up basing our heads against hard objects for a while, but we can
    figure this out.
    James Calivar, Apr 5, 2005
  9. DanG

    omni Guest

    What is the difference between G711/A and G711/U?

    Does the difference have any impact on sending faxes over IP, which
    version of the codec would be more appropriate?
    omni, Apr 5, 2005
  10. DanG

    DanG Guest

    The trouble with dropped calls and no dial tone appeared to have been a
    configuration issue. I was using DHCP rather than defining a static IP
    for my network. Per one Lingo techie's recommendation, I configured a
    static IP address, and I have not have a problem since (so far). I
    wish I could talk the that guy again. His explanation of the
    problem/resolution actually made sense. I haven't had much confidence
    in the other techies I've talked to.

    I figure the fax modem and the phone line are active. Incoming calls
    activate the caller id in the WinFax software. Sometimes I can even
    receive a page or two before the line is dropped. Outgoing faxes, via
    WinFax or Microsoft Fax, will even handshake with the receiving machine
    before disconnecting. It makes me think it's a protocol issue, or
    silence suppression. I hoped I could just add some options to the
    modem "AT" parameters, but nothing in the manual seems to deal with
    this problem.

    I've emailed Lingo twice, attempting to confirm what the techie said
    (the one I talked to about faxing). Even though they promise a
    response withing 24 hours, I've yet to receive one. (Maybe they're
    trying to fax the response to me.)

    I appreciate you're digging into this, James. I'm getting pretty
    frustrated with it.

    DanG, Apr 6, 2005
  11. The difference between G.711 A-law and G.711 u-Law (that's the Greek letter
    "mu" by the way) has only to do with the particular characteristics of the
    companding algorithm used. A-law and u-law companding are very similar, but
    for whatever reason, A-law is preferred in Europe (on E1 lines) and u-Law is
    used on North America (T1 lines). A-law companding provides a slightly
    larger dynamic range at the expense of inferior small-signal quality
    (slightly higher idle channel noise).

    There should be no discernible difference between then two as far as fax or
    modem performance is concerned on telephony lines. As for which is "more
    appropriate" for sending fax over IP, it's really a question of whether your
    IP-based media gateway exists in a T1 or E1 environment. That pretty much
    fixes your choice for you.

    James Calivar, Apr 6, 2005
  12. OK, so then it's probably not a case of your modem being disabled. Can you
    try my idea of hooking it up to a line that's not going through the cable
    box? Just a plain old telephone line. I suspect that you will be able to
    successfully make fax calls - if so , then it's definitely a case of
    something in the cable modem box screwing up your fax modem.

    As I said before, I'm not an expert on cable modem boxes, so I don't know
    the exact innards of what goes on inside of one, but it should not impede
    fax traffic if the ISP has properly configured their network. I'll ask
    around here at work and see if I can't get a good explanation of what
    happens inside a cable box. You've got my curiosity up and I'd like to hear
    an explanation of why it will or won't work.

    James Calivar, Apr 6, 2005
  13. DanG

    DanG Guest

    I don't have a direct phone line anymore. I didn't want to pay for a
    phone line just to send/receive the occasional fax. But I know it
    worked when I did have a phone line, before switching to cable.

    Here is an interesting article:
    It explains a lot, but doesn't actually say that FoIP is possible in
    the straight-forward way I want to.

    DanG, Apr 6, 2005
  14. Again, we have not definitively ruled out a config change on your PC as the
    culprit, although based on your earlier statements, I don't believe that
    this is the case anymore.
    Yes, I'm aware of most of the issues in this article. (I spent the past 3
    1/2 years developing fax relay software specifically for VoIP networks.)
    It's quite possible that the default codec in your system is a low-bit-rate
    voice-specific codec, which of course, fax won't go over. However, there
    should be "smarts" built into your cable system that detect when a fax is
    being sent, and automatically switch over from a low-bit-rate voice-specific
    codec to something that will accomodate fax (like G.711 u-Law, or even G.726
    32kbps). It's a good bet that this might be the cause of your problem.

    What is the make and model of your cable modem box? Maybe I can look up its
    spec cheet and get a better picture of what's involved here.

    James Calivar, Apr 6, 2005
  15. DanG

    DanG Guest

    The cable box is a Motorola SB5100.

    I've actually had a bit of a breakthrough, though. I tried setting the
    maximum bit rate on the modem down to 2400, and unchecked the ECM boxes
    (figuring those are Echo Cancelling options). I was able to send a
    fax!! I don't know if the ECM options made the difference, or what max
    speed I could use. Might take some tweeking and testing.

    DanG, Apr 6, 2005
  16. DanG

    wkearney99 Guest

    I figure the fax modem and the phone line are active. Incoming calls
    I can't seem to find the web link but I do recall there being some serious
    timing hassles with 'generic faxing' and VoIP and it had everything to do
    with a fundamental incompatibility between the timing of faxing and TCP/IP
    traffic and various codecs involved. In short, faxing using 'real' fax
    hardware over voip channels is very much a crapshoot. As in, quite unlikely
    to work reliably.
    wkearney99, Apr 7, 2005
  17. DanG

    Rick Merrill Guest

    Thanks for clearing that up.

    I wonder what methods are used by ?
    Rick Merrill, Apr 7, 2005
  18. ECM = "Error Correction Mode". This basically means that the page data is
    HDLC-encoded into blocks of data, and if the receiver dow not receive the
    data with the same calculated checksum as is transmitted, the data is
    resent. The problem with this on packet networks, however, is that if you
    have significant packet loss, it's quite possible that some blocks of data
    will never get through error-free before the T.30 ECM protocol decides that
    it's had enough and terminates the call. Hence, you miss entire pages,
    instead of just getting a few garbled scan lines on the page (which the
    human eye can typically interpolate for you).

    It's ridiculous that you should have to slow the fax modem down to 2400 bps.
    That's the lowest speed available. You should be perfectly capable of
    sending non-ECM faxes at the full rate of 14400bps. If not, that says quite
    a bit about the health of Lingo's packet network.

    James Calivar, Apr 7, 2005
  19. The fundamental problem is that faxing is based on a real-time protocol
    (based on the ITU Recommendation T.30), and has very strict timing
    requirements. Packet networks, by nature, are non-real-time, with packets
    arriving late or never at all (latency/packet loss), out of order, and with
    varying inter-packet delivery times (jitter). Most ISPs are going to take
    the cheap route and offer "fax and modem service" by routing fax and modem
    traffic through the G.711 64kbps codec. This is fine and well, as long as
    the packet network is well-managed and has very little degradation
    (specifically, packet loss). However, as soon as packet loss exceeds a
    small threshold (often as little as 0.1%), the ratio of failed and
    terminated calls due to failed negotiations, lost data, out of synch modem
    PLLs, etc. rises markedly. That is why it is important for providers of fax
    and modem over networks to employ dedicated FoP or MoP (Fax or Mode over
    Packet) solutions - usually in the form of FoIP or MoIP (IP => Internet
    Protocol). The problem is that ISPs are cheap bastards and they don't want
    to incur the cost of deploying these solutions. The result is that their
    customers get screwed.

    The case can be made, of course, that since a user of an IP network already
    has network access, he can just email the file to the recipient instead of
    faxing it. This has some truth to it, but it's not always valid.
    Specifically, some non-English languages (like Mandarin) are represented in
    a very limited way on PCs, so it's often easier just to write something out
    longhand and fax it.

    The debate goes on...
    James Calivar, Apr 7, 2005
  20. DanG

    DanG Guest

    Another case can be made, too. Just because the user of an IP network
    has access doesn't mean the recipient does, which is my case. Several
    of the people to whom I need to send/receive documents do not even have

    I'm still not sure if I ever got an answer, though. Lingo says they
    support FoIP, but not T.38. If T.37 (store and forward) works, will a
    fax machine (rather than a PC) do that (as Lingo said it would), or
    does it require other hardware/software? Or is Lingo not exactly
    telling the truth about their ability to support FoIP?

    DanG, Apr 7, 2005
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