U.S. Robotics Sportster 28800 Modem Does Not Function with RAS (139470)


The information in this article applies to:

  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Server 3.5
  • Microsoft Windows NT Server 3.51
This article was previously published under Q139470

SYMPTOMS

Some models of the U.S. Robotics Sportster 28800 V.34 and V.FC modems do not work with Remote Access Service and some other communications software. However, the same modems sometimes appear to function properly with Windows Terminal or other communications software.

CAUSE

The U.S. Robotics Sportster 28800 V.34 modem is not on the Windows NT 3.51 Hardware Compatibility List (HCL). Some newer U.S. Robotics Sportster 28800 V.34 and V.FC modems have updated circuitry or firmware. The updated modems function like a U.S. Robotics Sportster 33600/Fax V1.0 or V1.1 modem instead of a Sportster 28800. When you use a similar model to connect to the Sportster 28800, the two modems appear to connect at 33,600 baud. There are some differences with the initialization strings of the Sportster 28800 and the 33600 model.

To verify the firmware version of your U.S. Robotics Sportster fax/modem:
  1. Start the Terminal tool in the Windows NT Accessories group.
  2. Properly configure the communications settings for your fax/modem.
  3. Type "ATI3" (without quotation marks). This will tell you which firmware version you have.
NOTE: If you have Remote Access Service installed, you may need to stop the Remote Access service, using the Services tool in Control Panel, before you receive an appropriate response from the modem.

RESOLUTION

To correct this problem, do one of the following:
  • Obtain an updated Modem.inf file from U.S. Robotics at (847) 982-5151 (technical support) or (847) 982-5092 (BBS).

    -or-
  1. In Terminal type the following:

    ATI3
    1. If the modem responds with "Sportster 33600/Fax V1.0," proceed with step 2.
    2. If the modem responds with "Sportster 33600/Fax V1.1," proceed with step 2, except that you will have to change the following:

      DETECT_RESPONSE=Sportster 33600/Fax V1.0

      to this:

      DETECT_RESPONSE=Sportster 33600/Fax V1.1
  2. Update the existing Modem.inf file by appending the

    US Robotics Sportster 33600 V34

    section, as follows:

    [US Robotics Sportster 33600 V34]

    <speaker_on>=m1
    <speaker_off>=m0
    <hwflowcontrol_on>=&h1&r2
    <hwflowcontrol_off>=&h0&r1
    <compression_on>=&k3
    <compression_off>=&k0
    <protocol_on>=&m4
    <protocol_off>=&m0
    <autodial_on>=ATdt
    <autodial_off>=ATd

    CALLBACKTIME=10
    DEFAULTOFF=compression
    MAXCARRIERBPS=33600
    MAXCONNECTBPS=115200

    DETECT_STRING=ATI3<cr>
    DETECT_RESPONSE=Sportster 33600/Fax V1.0

    COMMAND_INIT=AT&a3x4e1q0v1s0=0s7=55s2=128<cr>
    COMMAND_INIT=AT&b1&c1&d2b0x4<hwflowcontrol><compression><protocol> <speaker><cr>
    COMMAND_DIAL=<autodial><phonenumber><cr>
    COMMAND_LISTEN=ATS0=1<cr>
  3. Change MAXCARRIERBPS to 33600.
NOTE: The MAXCONNECTBPS can be changed to be as high as 115200. Some serial ports cannot handle the 115200 baud rate accurately and may work more reliably at 57600. This behavior may be computer dependent.

For the U.S. Robotics Sportster 28800 v.34 and v.fc modem hardware revision level 2.0, you should select the preexisting entry in the Modem.inf file. The entry is called:

US Robotics Courier V.32bis


If you are using multiple Sportster 33600 modems that have different firmware versions, either obtain a firmware upgrade from US Robotics, or add to the Modem.inf file another section with a different name to support the other version(s) of firmware.

MORE INFORMATION

Aside from the different detection responses, the main difference between the initialization strings of the two modems is that the Sportster 33600 lacks the S47 register. The U.S. Robotics generic initialization string should work for the Sportster 33600 modem if the S47=2 entry does not exist.

Some models may have a different response string based on their firmware version. To verify the response string from your modem, use the Terminal tool to issue the ATI3 command to the modem. This displays the response string. The Modem.inf entry above may need to be modified to match the response of the modem.

The products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

The third-party contact information included in this article is provided to help you find the technical support you need. This contact information is subject to change without notice. Microsoft in no way guarantees the accuracy of this third-party contact information.

Modification Type:MajorLast Reviewed:12/16/2003
Keywords:KB139470
©2003 Microsoft Corporation. All rights reserved.