This forum will not take HTML codes. Nice help.
OK, I am using a Huawei Model. But that is supplied by my Internet connection provider: Reliance Communications. Its very easy to install and use in Windows 7 (64 bit) : just plug it and the driver will be installed from the modem part itself. However you can download from their website too.
But the dialup interface is Reliance's custom made. You can install the driver and use Windows dial up utility to connect to the internet. You are installing the driver, but not using the Reliance dialer. OK?
But before that, I will suggest you to visit this forum: India Broadband Forum
You can refer to this post, they will understand it easily
Though its an Indian forum, they can help you as most of the helpful and knowledgeable active users are either Hardware or Software Engineers.