Subj : A little help... To : Mike Luther From : Peter Knapper Date : Sun Jul 23 2006 11:35 am Hi Mike, ML> In contemplation for yet another fallback ML> vector for disaster relief emergency setups using OS/2 ML> and the old BBS system game. Have you ever tried using ML> VOIP and 'standard' modem connections to the FidoNet ML> stuff over VOIP? If you effectively mean a modem connection over VoIP, then forget it, your chances of anything working are near zero. We do Voice PABX Tie lines using VoIP and 30 voice channels will still use up around 700Kb of IP bandwidth (including VoIP management traffic), and no Modems or Faxes work on that. "Real" Voice (and Fax, modem) calls need bandwidth, in fact a "standard" Telco voice grade "circuit" uses 64Kb digital channels (for most of the globe except USA where many areas still use 56Kb) to pass pure voice circuits. These "channels" use minimal Analog to Digital "conversion" or encoding protocols and can pass good quality voice, modems, and fax traffic no problem, however to maximise the available bandwidth, Telco's now often use various compression schemes to reduce the needed bandwidth (maximise ROI) and there is no ONE compression scheme that works well for Voice, Modem and Fax. Voice is now regularly compressed to around 8Kb per channel, and fax is similar at around 14Kb (for an effective 9600bps Fax connections), however a modem modulation scheme designed to work at 56Kb has bugger all room left for any compression scheme to be applied. ML> But I'd like to know what the answer to that question ML> might be. Could be an interesting fall-back down a ML> long an lonely road at the other end of 'someplace' ML> where the wolf has alrady eaten both Hansel and Gretal. Think about it. In a pure copper line situation, Digital Data from a PC is MODULATED by a modem into Analog signals, which is then DEMODULATED back to Digital again for the receiving PC. The result is something like this - Digital ==> Modulated to Analog ==> Demodulated to Digital. Using Voip, you would using be something like this - Digital ==> Compressed/Encoded to VoIP ==> Expanded/Decoded to Digital ==> Modulated to Analog ==> Demodulated to Digital. So you are adding extra conversion steps that MUST degrade the quality of the ANALOG component of the service. And the compression possible for a Modem signal is MUCH harder to achieve due to the inherrent bandwidth requirements for an Analog Modem Modulation scheme (such as V.92). Sort of related to all this, but one of my big gripes abot the descriptions provided for the broadband community is that "broadband" communications ALL use a PURE DIGITAL transmission format, they have left the dial-up world that uses the ANALOG tansmission formats. That means ADSL, CABLE, in fact ALL modern WAN transmisison formats are PURE DIGITAL in nature, therefore NONE of these device are MODEMS, they do not MODulate and DEModulate anything. They actually ENCODE and DECODE everything. So what on POTS is known as a MODEM should (technically) for broadband be known as a CODEC (enCOde, DECcoder). however humans being what we are dont; like change so the term MODEM has hung around... One of the BIG issues with Ananlog data such as voice is Latency, humans cannot stand more than about 200ms of delay in getting voice data from one place to another to be able to hold a "normal" conversation between 2 people. ANY time we convert data between 2 formats we induce a delay, and the largest delay in modern tranmission systems is when MODULATING and DEMODULATING data. The more conversion steps, the worse off you wil be. This is why trying to run voice over Analog modem connections will never achieve the same level of quality of service as over a pure digital path such as broadband. Yes it may work fine for local calls, but for long distance, well that has many variables that are hard to predict. Also if you use VoIP only to connect to a LOCAL Exchange and your calls go via standard voice methods from there, then you have the best possible introduction into VoIP. ML> I've already got the OS/2 world up and proofed via the Hughes bird. And what may be a "Hughes" bird??? ML> But as a last resort if nothing else game, I wonder if ML> VOIP could be used to take the BBS game (Fido) to a ML> place where curiously, only phone line support existed? Yes, in theory it could, but I predict that you would to be HUGELY disappointed with the result........;-( Lastly, remember that an Analog Modulation scheme is 100% Analog signal the ENTIRE time a MODEM call is established (IE while the modem has Carrier present on the line), REGARDLESS of any digital traffic flowing. With voice traffic, a person does not talk 100% of the time, when there is no voice traffic, there is minimal (if any) VoIP traffic. Fax manages to work around this because it is 99.9% one way traffic and it uses highly optimised modualation schemes that enable compression to work very well on it. Voice is not quite so... predictable. ML> And thus pull the cost effectively to zero to create a ML> long term time connection to someplace that needed it, ML> yet by old phone line slower but effective use? Odly enough, the best way t oachieve this is to go 100% digital from machien to machien communiacitons, the fewer "conversion" steps, the better the quality of service and Bandwidth utiliisation and therefore a lower operational cost. As I see it, the answer is to get ALL users onto some sort of "broadband" (in this context meaning a permanent digital transmission path) connection (even 64Kb could work wonders for many people), where digital data is all that has to flow and this bypasses so many conversion isses. Ultimately the "problem" in all this is the HUMAN BEING, they need ANALOG signaling, so the optimum configuration is where the ONLY Analog to Digital conversion would be at the Human interface points at each end of a connection. Either that or someone comes up with a better way to ship analog data round and forget the conversion points..........;-) Cheers.........pk. --- Maximus/2 3.01 * Origin: Another Good Point About OS/2 (3:772/1.10) .