Installing an Unlisted RAS Modem

The information in this article applies to:

• Microsoft Windows for Workgroups, version 3.11

NOTE: Microsoft does not encourage nor support user changes to .INF files; therefore, Microsoft Product Support Services (PSS) does not support the procedure in this article. Although we have tested the following procedure and it appears to function as described; we strongly recommend that you make a backup copy of your .INF file before you proceed.

SUMMARY

It is possible to install an unsupported modem for use with RAS only, even though the modem does not appear on the list of supported communications devices. Although not tested by Microsoft, many devices can operate satisfactorily. To set up an unsupported modem for RAS, it may be necessary to edit the MODEM.INF file or to choose an emulation. This article provides an example to guide you through this process.

MORE INFORMATION

The parameters for your modem can be substituted for the parameters in the example below.

Example

You are using a Macronix Stealth 144 modem, which is not included on the list of approved modems. After trying to install the Stealth 144 as a different Macronix modem (such as the Maxlite Fax 9696 or the VOMAX 2000), the modem still does not work correctly.

Because most modems are Hayes compatible, configure your modem as a Hayes Compatible 9600. If it works correctly, you can edit the MODEM.INF file to include an option for your modem. Use the following steps to do this:

1. Back up the existing MODEM.INF file. Then open the MODEM.INF file in your Windows SYSTEM subdirectory, and search for the heading [Hayes Compatible 9600]. Select the entire section and choose Copy from the Edit menu.

   The section appears similar to the following:

         [Hayes Compatible 9600]
         <speaker_on>=M1
         <speaker_off>=M0
         <autodial_on>=ATDT
         <autodial_off>=ATX3D
         CALLBACKTIME=10
         DEFAULTOFF=compression
         MAXCARRIERBPS=9600
         MAXCONNECTBPS=9600
   

         COMMAND_INIT=AT&F&C1&D2 V1 S0=0 S2=128 S7=55<speaker><cr>
         COMMAND_DIAL=<autodial><phonenumber><cr>
         COMMAND_LISTEN=ATS0=1<cr>
   

2. Move to the end of MODEM.INF. From the Edit menu, choose Paste so that the Hayes information can easily be found later. Change the heading on the pasted information from [Hayes Compatible 9600] to [Macronix Stealth 144].

3. The Stealth 144 is a 14,400 baud modem; however, because of software or hardware compression, it is possible to connect at a higher rate. You can modify the information pasted in step 2 so that the modem attempts to connect at 19,200.

   The MAXCARRIERBPS= is the maximum baud rate for this modem. Change this from 9600 to 19200. The MAXCONNECTBPS= is the baud rate at which negotiating (training) begins when the modem is connected. If the two modems cannot talk at this rate, lower rates are automatically tried until a baud rate at which both modems can operate is found. Change MAXCONNECTBPS= from 9600 to 19200.

4. Load RAS. Choose Setup, then choose Configuration. The new modem should now appear under Device. Select it and restart RAS to load the information for the new modem.

   When you install a RAS modem, the installation program reads the MODEM.INF file, parses the information for that particular modem, and writes part of it to the SERIAL.INI file. When RAS is loaded, it reads both the SERIAL.INI and MODEM.INF files. Therefore, after making any changes to the MODEM.INF file, reinstall the modem.