Make sure you have the full AT commands spec for your modem!

For "programmatic" use I concur with Phillip - use the numeric response codes (V0) rather than Verbose (V1), which are intended for manual use by a human operator.
It is much easier for software to handle numeric codes than to have to parse "human readable" strings.

If a Win9x INF file is available for the modem, you could look at that - it's just a text file!