Hello there... I've come to offer a few starter tips to help you get the help you need for the modem you have.
1.. Please add your Linux Distribution to your profile.
2.. Check the HCL (link atop this page) and see if there is another user(s) here or any reviews about the particular modem you have, and maybe tips on getting it working.
3.. Be specific about what help you need: Tell us what is the modem make/model, is it dialup or broadband, what sort of computer you are using, etc.. The more details you have to start with, the less must be filled in with subsequent posts.
4.. The Linux User Group thread is for Linux User Group information. If you post in your Distribution's forum, or in the hardware forum in the appropriate area, you will get much more attention to the issue at hand.
Welcome to Linux!
