The term "modemname" Windows driver is a bit vague, but I believe you're referring to the driver for a modem device in Windows, often called something like "modem driver" or a specific modem's name, which allows your Windows computer to communicate with the modem hardware. A modem is used for connecting to the internet over a phone line (in the case of dial-up modems) or for cellular connections (in the case of mobile broadband modems or USB dongles).

To clarify, a modem driver is software that tells your computer how to communicate with and use the modem hardware. The name "modemname" would likely refer to the specific name of the modem device, such as "Huawei Mobile Broadband Modem" or "Motorola USB Modem," etc.