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 T.38.
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).
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.
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.
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 missed?
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)
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 exchanged.
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.
"DanG" wrote in message news: firstname.lastname@example.org...
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.
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.
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.
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.
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.
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.
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.
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 email.
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?
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.
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.