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   |               Troubleshooting the Intel 2400B Modem 2                   |
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    CARRIER ALREADY ESTABLISHED MESSAGE

        Carrier already established/Already on line
        This error can happen when the modem is on line when entering a
        communications package OR our 2400bps (non-MNP) modems are set to
        factory configurations. When shipped from the factory, carrier detect
        is on at all times, just like a Hayes 2400. To correct this problem,
        issue:

            AT&C1&D2&W

        This causes carrier detect to represent the true state of what the
        connection status is. The &D2 will cause the modem to hang up the phone
        when DTR is dropped, which is also desired for most communication
        packages.


    USING COM3/COM4 UNDER WINDOWS 3.0

        If you have problems using the your modem on COM3 or COM4 under Windows
        3.0, exit Windows and use Intel's TESTCOM.EXE program (which comes with
        all Intel modems) to test your modem.  TESTCOM performs several
        diagnostic tests on the modem and helps you verify the phone line
        connection.  SatisFAXtion board users who need a copy of TESTCOM can
        order document 0018 from Intel's FaxBACK system.  Modem users can
        download TESTCOM from the Fax/Modem section of Intel's BBS.

        Once you know the modem works on COM3 or COM4 outside of Windows, you
        can test the modem with your Windows program.  If you run Windows in
        Enhanced mode, you need edit the Windows SYS.INI file.  Under the
        [386enh] symbol, add these lines:

        COM1BASE=3F8h
        COM2BASE=2F8h
        COM3BASE=3E8h
        COM4BASE=2E8h

        Editing your INI files is risky business.  Carefully read your Windows
        documentation or call Microsoft Microsoft Technical Support if you
        questions or problems.

        Microsoft Tech Support:  206-454-2030









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   |               Troubleshooting the Intel 2400B Modem 2                   |
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    DETECTING PORTS WITH DEBUG

        By using debug you can determine what COM ports are in the system. KEEP
        IN MIND THAT THIS WILL ONLY SHOW THE PRESENCE OF COM 1 AND COM 2:

        debug
        -d40:0
        0040:0000  F8 03 F8 02 00 00 00 00-BC 03 00 00 00 00 00 00 00 00

        This display indicates the presence of a COM 1 (03F8) and a COM 2
        (02F8). Note that the address bytes are reversed!

        If you want to know what COM ports are in the system (including COM
        3&4), use TESTCOM Version 4.0 or newer (available at FSI). Issue
        "TESTCOM /S" at the DOS prompt.


    DO YOU HAVE A DIGITAL PHONE LINE?

        Conventional modems, including Intel's, will NOT work with digital
        phone systems. Digital phone systems (Rolm, Aspect, etc...) convert
        digital signals back to sound and from sound into digital for clearer
        communication. All of this conversion is done in each end of the
        telephone which is not something that is present in a data modem. All
        digital phone systems are different. To use a modem on a digital line,
        an A to D & D to A converter is needed. Each A to D converter is
        specific to each phone system. Have your customer contact their phone
        company for more details.A good way to identify a digital phone system
        is to look on the phone for things like "Voice mail" buttons and
        "Message waiting" lights. Most of the time these features are only
        available in digital phone systems.


    ERRATIC RESPONSE TO AT COMMANDS

        Erratic response to AT commands can be attributed to two things: IRQ
        Conflicts and/or COM port overlaps.  You can use the  TESTCOM.EXE
        program can verify modem operation and detect conflicts.

        First ensure that no other devices are using the same IRQ as the modem.
        Modems use IRQs to signal the computer that data has been received or
        sent. For an internal modem, make sure that the COM port it's set to
        does not conflict with a COM port already in the system (whether used
        or not). When in doubt, try another COM port setting.

            Port   I/O   IRQ
            ----   ---   ---
            COM1   3E8    4
            COM2   2E8    3
            COM3   3F8    4
            COM4   2F8    3

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   |               Troubleshooting the Intel 2400B Modem 2                   |
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   |============================== (continued) ==============================|

        For instance, consider a situation where you add an internal modem to a
        system which has COM1 and COM2 built in. There's a mouse on COM1 and
        nothing on COM2.  You must either:

           Disable the built-in COM2 and address the modem as COM2 (prefered)
           Leave the mouse on COM1 and address the modem as COM4
           Move the mouse to COM2 and address the modem as COM3


    INTERMITTENT SWITCH TO COMMAND MODE

        If your modem intermittently switches to command mode while on line,
        change the DTR option:

        AT&D2&W


    LEASED LINE SETUP

        If modems fail to communicate over leased lines, but work fine on
        standard lines, issue "AT&L1" to the modem. The default is &L0. Refer
        to the modem guide for more information.

        In addition, if the leased line is a 4 wire line rather than a 2 wire
        line, a 4 wire to 2 wire converter will be required. This converter can
        be obtained from their phone company.


    MAKE IT A HAYES WHEN IT DOESN'T WORK!


        If you are having problems with an MNP based modem that seem to be
        unresolvable, turn off all of the extra features in our MNP modems.
        Issue "AT&F\N0\Q0\V0\J1&W". This will make the modem look exactly like
        a Hayes 2400.


    MANUAL DIALING (EXISTING CONNECTION)

        If someone tries to use the manual dialing method explained in the
        manual they will receive a message of "NO DIALTONE". Use the following
        instead:

           o           Get into the terminal mode of your communications
                       package.
           o           Dial the number and wait for the phone to start ringing.
                                       -OR-
           o Finish talking to the other person.
           o Type ATH1 to have the modem pick up the phone
           o Type ATO (letter O, not ZERO!) to instruct the modem to go
            on line.

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   |               Troubleshooting the Intel 2400B Modem 2                   |
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    MODEM ANSWERS ONLY AT 300 BAUD

        This problem affects only two Intel modems: the 2400EX MNP and the 2400
        Classic MNP modems.  If either of these modems is set to auto-answer
        and a call comes in at 300 baud, all subsequent calls will connect at
        300 baud.  To eliminate the condition, you must turn the modem off,
        wait a few seconds, then turn it back on.

        This problem affects only incoming calls, not outgoing calls.


    MODEM DIALS BUT DOES NOT CONNECT

        Modem Dials but Does Not Connnect
        This problem commonly results when your modem is set to use MNP but the
        remote modem doesn't support MNP.  It can also happen if the value in
        your modem's  S7 register is too low.  The value in the S7 register
        tells the modem how long  to wait for a carrier signal after dialing.

        To find out if MNP is causing the problem, enter the command:  AT\N0&W.
        If the problem persists, make your modem act like a Hayes modem by
        entering the command for your modem:

            Intel Modem           Command
            -----------------     -----------------------
            SatisFAXtion          AT&F\N0\Q0\J1\V0&W
            14.4EX/9600EX         AT&f\N0\Q0\J1\V0"H-J0&W
            All 2400 Baud MNP     AT&F\N0\Q0\J1\V0&W

        To find out if the value in the S7 register is causing the problem,
        increace the value from its default of 30 seconds. Run the TESTCOM
        program, select the "Terminal emulation mode", then type   ATS7=60&W
        and press ENTER. If this doesn't help, try a higher value (the maximum
        is 255).

        Here are the common symptoms of an MNP problem:

        Your modem dials, the remote modem answers, the modem tones begin, then
        either:
        a.  your modem hangs up, or
        b.  your modem does nothing while the tones continue.

        If the user still can't connect after disabling MNP, try calling the
        system  yourself. If they're using a SatisFAXtion modem, make sure they
        have the latest software. If not, they can order 0011 from Faxback.







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   |               Troubleshooting the Intel 2400B Modem 2                   |
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    MODEM MAKES CONNECTION THEN HANGS UP

        Modem makes connection and then hangs up
        There are two possible causes:

        The modem on the other end is not MNP capable and can't deal with the
        MNP starup sequence. The solution to this is to issue "AT\N0" to
        disable MNP.

        Secondly, the "wait time for answer" register may not be set long
        enough. Try ATS7=90 (or something longer than what it is set to).
        Sometimes international and/or long distance lines take longer than 30
        seconds (default) to connect. Keep in mind that there is a similar
        setting in most terminal programs when auto-dialing.Make sure that the
        "Wait time for answer" in your communication package is set to S7's
        value (or higher).


    MODEM STUCK IN LEASED-LINE MODE

        If you set the modem to Leased-Line mode and Synchronous mode, here's
        the only way to reconfigure the modem:

        1.  Make a connection with another modem.
        2.  Enter +++ to put the modem into command mode.
        3.  Enter AT&F to turn off Leased-Line and Synchronous mode.

        When in Leased-Line mode, the modem tries to establish a connection as
        soon as you turn it on.  The modem doesn't receive commands until after
        it establishes a connection.


    MODEM SUDDENLY DISCONNECTS

        Intel MNP based modem (SatisFAXtion, 9600EX, etc...) have an inactivity
        timer which hangs up after a predetermined amount of time with no data
        sent or received. The remote modem disconnecting could be caused also
        by extremely noisy lines. Try issuing "AT\T0" to disable the inactivity
        timer. Try the call again.

        Keep in mind most bulletin board systems will disconnect if no data is
        sent or received within a predetermined amount of time.


    MODEM COMMANDS BUT DOESN'T ECHO CHARS

        First, issue "AT&F" to the modem to ensure that echo and result codes
        are turned on. If that doesn't work, look for IRQ conflicts and/or COM
        port overlaps (with internal modems). The modem tells the computer that
        data has come in by using interrupts. If no interrupts are generated,
        no characters will be received or echoed.

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   |               Troubleshooting the Intel 2400B Modem 2                   |
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   |============================== (continued) ==============================|

    MODEM WON'T ANSWER THE PHONE

        There are two reasons why the modem won't answer:

        1.  The modem isn't in Auto-Answer mode.
        2.  The modem doesn't see the DTR signal from the computer.

        The command ATS0 controls Auto-Answer mode.  An external modem turns on
        "AA" light on when Auto-Answer mode is enabled.

            ATS0=0    disables Auto-Answer
            ATS0=1    answer after 1 ring

        The command AT&D controls how the modem responds to the computer's DTR
        signal.  An external modem turns on the "TR" light when it sees or is
        set to ignore the DTR signal.  If the "TR" light isn't on, the modem
        won't answer whether Auto-Answer is enabled or not.

            AT&D0     Modem ignores DTR signal
            AT&D2     Modem swtches from data to command mode, hangs up
                      and disables Auto-Answer mode when DTR switches
                      from ON to OFF.

        Use AT&D0 if you serial port doesn't support the DTR signal or if your
        modem cable doesn't connect to it. Otherwise, use AT&D2. DTR is on pin
              20 of a 25-pin connector and on pin 4 of a 9-pin connector.


























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