Atari Jaguar Voice Modem (JVM) FAQ

We've all heard about it... some of us have dreamed about it. But we've always been told to think as if it doesn't exist. What is it? The Jaguar Voice Modem!!!


Owner's list updated 09/26/02.

  1. Does it really exist?

    Yes!!! There are a couple pictures out there on the Internet with photographs of them. Check at the Atari HeadQuarters in the Jaguar & Lynx Museum section. Also, see the Atari Historical Society site for a picture and brief description.

  2. How many exist?

    Sources indicate that less than 100 exist.

  3. Who are some people that own one?

    1. Carl Forhan --
    2. Curt Vendel --
    3. John Hardie --
    4. Keita Iida --
    5. Don Rogers --
    6. Dave Stein --
    7. Mike Etler --
    8. Guy Dupre --
    9. Ken Dupre --
    10. Mike Szoke --
    11. Scott Walters --
    12. Kevin Manne --
    13. Micah Rowe --
    14. Jason Data --
    15. Ted Rusniak --
    16. Matt Reichert --
    17. Jason Smith --

  4. What games work with it?

    As of this writing, only Ultra Vortek. Type '911' on the keypad during the title screen, and the program will attempt to initialize the modem. Only if you have one, though, can you proceed. But the background and lettering you see there are the ones used in all the modem screens.

    Note that various rumors exist that, for example, Iron Soldier 2 supports the JVM. Eclipse, the developer of IS and IS2, has confirmed this is not the case, so this rumor should be considered completely false.

    Of course, one can always dream that more games using it will come out...

  5. Did the Voice Modem come in a case?

    No. Carl and his brother Patrick purchased a pair of Pactec CM-86 project enclosures from All Electronics ( These cases are 2"x8.08"x6.25", and fit the modems perfectly (after some minor drilling in the side panels to expose the jacks, LEDs, and switches). We highly recommend them.

    Kevin Manne recommends a Radio Shack case:
    RSU 11339652 $11.99 Black 6 1/4 x 8 1/8 x 2 1/2

  6. How does UV play and handle with the modem?

    After initializing the modem, a menu comes up:

    The usual UV music plays in the background. Should you chose "Dial Opponent", you will be presented with some further prompts, telling you to enter a number. Using the keypad, you may enter up to 16 numbers, stars, pounds, or pauses. A dials the current number (which also is an available menu selection), B inserts a pause (a 1.5 second wait, sometimes needed at the beginning of the dial string, to allow the modem to properly take the line off hook), C backspaces the number, to correct mistakes.

    The "Answer Phone" option immediately picks up the phone and initiates handshaking, regardless of whether it is a person or a modem calling. If the modem does not get a reverse of the same dial tone sequence in response, it simply leaves the connection up. This way you can talk, and explain why you just did that to the person =).

    Note: Since the handshaking starts with a simple series of dial tones, selecting this function when the phone is not ringing is treated as a dial out. Fortunately, I believe it starts with the equivalent of '9', so it will not make a long distance call. I think.

    After connection, a menu very similar (lacking, I think, the single-player option; adding a hang-up option) to the turbo-enabled single-console version appears. From this point onward, it acts as if there were simply two players on one console (except for modem-specific messages, like "Connection Lost"). Each player can Pause, move about, etc., as if they were on one Jag and one TV.

    Read on for more details of UV + modem.

  7. At what speeds does it run?

    The official specifications name five different speeds: 19200, 16800, 14400, 12000, 9600. However, UV most often connects at 16800, 19200, or 9600 (in that order). Primary difference among the three is quality of sound.

  8. Does it work well? How reliable is it? How often does it lose its connection?

    It does work. And it works moderately well. Only at its very worst performance do you even notice anything like 'lag' on the internet, or, in other words, slowdowns in gameplay. Usually, it does extremely well.

    However, its reliability seems to be heavily dependent upon the quality of the phone lines of your city. There are reports of extended long play, over long distance, even. My experience has been mixed.

    Interestingly, connecting at a higher rate (19200) is not necessarily better than at a lower one. For instance, the most stable experience can be had at 16800, and, at least in Rochester, Minnesota, this is the most common connect speed. We had no problems at this speed.

    At 19200, the connection seems particularly unstable, sometimes even hanging up on the spur of the moment. The voice is clearest here, of course, but the gameplay will frequently slow to a crawl, sometimes recovering, sometimes not. I suspect that the modem is having some kind of difficulty if a line suddenly goes bad. Similar problems seem to occur when connections are on the low end, too.

    Looking at the documentation, it seems that the software can request a speed. Perhaps this could allow for more consistent connections when the highest speeds are either not needed or not stable.

  9. How does the voice sound?

    The voice is always understandable, even at the lowest speeds. Of course, the quality goes down as the data connect rate goes down. This is especially noticeable at 9600, where voice sounds especially tinny. Sample rates are always less than 8000/second (see Technical Specs), for those of you who have played with sound cards...

    Of course, there are some problems. It may just be our (admittedly kinda cheap) microphone headsets, but there seems to be some kind of echo effect feedback. If only one microphone is hooked up, there seems to be no problem. But if you have two, and you talk too loudly, you will get a loud scream in your ear. This usually subsides within a second or so. Two ways to work around this: keep the headphone off your ear, or talk quietly!

    Of course, when you beat somebody up (like you tend to do in UV) it is hard not to gloat loudly.

  10. Can you play without headphones and a microphone?

    Absolutely. But believe me, you will be missing out on a lot. There is nothing like the gurgles and cries of a dying friend. Of course, you save yourself from some of the loud mishaps that happen from time to time (see Sound).

    Please note here that if only one person has a microphone plugged in, that person is liable to say some pretty crazy things... I guess they just get lonely... after all, the only way they know if anyone is listening is when they see someone lop off their head on the game!

  11. Is it documented?

    Yes, it is. The official Jaguar Development System specifications include an entire "Jaguar Voice Modem" section. The section is 22 pages long, and contains a lot of text, tables, flowcharts, and a command reference. Below I have included some of them.

  12. What are the technical specifications?

    Technically, there are a lot of these.

  13. What kind of chips and stuff are on the board?

    I'll only list the biggest/most interesting looking things, since there seem to be one to two hundred components on the board. And I'm not much on chips and stuff, so these are just guesses of the chip numbers/names...

  14. What sorts of inputs and outputs are on the modem?

    There are a bunch of cables/jacks/switches/lights:

Needs: info on pass-thru... info on data light... menu control and appearance comparison(Turbo-no modem and modem-connected)... Read more about DTMF sequence...

© 1997 Patrick Forhan