Historically, a dongle has been a hardware device that must be plugged into a computer for an associated program to run. Prior to USB, the dongle usually plugged into a serial port, and usually included a "pass through" so that a normal serial device could also still be plugged in.

In that context, dongles that didn't fail to work with the intended program did, almost universally, fail to work with any device connected in pass through mode.

A dongle of that kind has generally and universally, ALWAYS been considered the hallmark of INCOMPETENT PROGRAM DESIGN.

Now we call such things "DRM CRAP."

In all likelihood, your device isn't really a dongle in the original sense, but is just a "plug in modem" intended to communicate at the specific frequencies and with the protocols used by the phone service.

A problem with Vista and USB is that as soon as a device is plugged into a USB port, the OS attempts to identify the device and install a suitable driver for it. If the device is plugged in before the associated program is installed, an inappropriate driver may be installed. It can be difficult to remove a "wrong driver."

Cleverly, some USB devices that require a specific program still incorporate the donglish feature of requiring the dongle to be present before the program can be installed correctly/completely. This means that attempting to install the program first results in a defective software installation, but installing the device first results in a defective USB driver installation. Once either program or driver is incorrectly installed, removal may be difficult and subsequent reinstallations (even in correct order) may repeatedly fail.

I can't say that this is a problem with the installation at hand; but stupidity is abundently evident in the ranks of designers (esp those who would call anything a dongle).

Your first steps might be to read the installation instructions carefully, and try to remember exactly the order in which each step was performed to assure that it was all done "by the book."

If anything was out of step, you might need to:

1. Uninstall the program.
2. Disconnect (remove) the dongle.
3. Use Device Manager to disable all the USB ports.
4. Shut down the computer.¹
5. Disconnect ALL USB DEVICES.
6. Reboot.²
7. Connect each of the other USB devices one at a time, allowing the OS to find and install drivers for each one in turn.
8. Reinstall the program and dongle/modem exactly according to the instructions.

This should work in about 26% (?) of all cases. I've never seen instructions for what to do with the other 87%.

¹ Since Vista (like most other OS versions) doesn't identify what devices are connected to which USB port, if you use a USB mouse or keyboard, you may find shutting down something of a puzzle.

² If you did a BRS shutdown (Big Red Switch = disconnect power) you might want to reboot, connect only the appropriate USB mouse/keyboard, and then REBOOT to assure everything is stable before proceeding with connection of other USB devices.

As my comments are based on "general principles related to USB devices" any specific advice from those familiar with your hardware/program should take precedence.

John