The first step is to identify your modem,
visit the following site and use the scan modem tool to identify ur modem.
Once you are able to identify your modem, go to
u can use the linuxant modem identifier tool as well:
depending upon the results, download and install the appropriate driver.
One thing to keep in mind, dere r two versions of modem drivers by linuxant
1) Free version (that supports a data transfer rate of 14kbps)
2) paid version (costs u around $20 and supports a full data transfer rate of 56kbps)
u can find the paid version via torrent (if u feel, it's right for you)