I have had good luck with the 2.7.10 smartlink driver with the 2.4 kernel series. The later driver works for the 2.6 kernel series but is a little more difficult to install
Modems based on Intel chips (HaM/536ep/537).
* Intel 537 kernel 2.6 available under Intel/537 courtesy of Alexander Komarov - 13/8/04 (not yet on Intel site)
* The Intel HaM Driver version 3.33 is the only version to work with 2.2.x kernels.
* New Linux modems drivers (536,537) are posted on the Intel Web site.
Many older installers are also stored on this site
See both locations (specially bottom of Intel site) for some ready-to-go packages
You still may want to note that the SmartLink slmdm driver up to release 2.7.10 or starting from 2.9.1, not those in between, usually supports this chip
From this Web site:
Linmodem Resources