Globalstar Product Management – Technical Support

Windows 2000/XP Modem Bug

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I have installed the modem on my Windows 2000 (or Windows XP) system and when I press the DIAL button on Windows, I get a dialog box which reports that the modem is not functioning properly or that there is no dial tone.

Answer: There is a bug in Windows 2000 and XP whereby the modem is assigned to the wrong COM port in the underlying application layers. At the user level, all looks well, but the problem is that Windows is actually communicating to a different COM port without telling the user. This bug will occur even if you add one of Windows’s own modem drivers or even if you add a modem for a cellular carrier. This bug is not specific to Globalstar and has nothing to do with Globalstar.

The good news is that it is fairly easy to get around this Windows bug. The bad news is that this can recur without warning. Therefore, we recommend that you store this technical note in a file on your computer so that you will be able to quickly recover from this bug if you ever encounter it again.

=============== QUICK SOLUTION: ===============

The quickest solution is to simply re-install the modem driver because usually, Windows 2000/XP uses the correct COM port the second time a modem driver is installed.

Use the instructions in Step 2, below, to install the modem driver.


1. Make sure that the COM port is functional. Do this by running HyperTerminal to connect directly to the port. In other words, go to

File ==> Properties ==> Connect Using ==> COMx

Then configure the COM port to run at 38400 (use 19200 if this is a GSP-2900). Ensure that you can type AT commands to the phone and that it responds. For example:

AT$QCSTATUS should respond with multiline info about the phone.

Dial a nearby landline or cellular phone and see if it rings: ATD1-AreaCode-PhoneNumber

If you are able to communicate with the modem by connecting DIRECTLY to the COM port, then the problem is with the modem driver and, most likely, the COM port bug.

If the computer COM port cannot communicate with the phone, there is no way that the computer will be able to set up a data connection.

Fix any problems with the COM port before proceeding any further.

2. If you are still having problems, then open the Windows Control Panel and add the modem AGAIN.

Control Panel ==> Phones & Modems ==> Modems ==> Add ==> Standard 28800 (or Standard 19200 if a GSP-2900)

Assign the modem driver to the COM port.

3. Once you have a working modem configuration, go back into Windows Control Panel and delete all the extra non-working modem definitions.

Written by Joseph Crowley

June 16, 2017 at 7:11 am

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