Zoom currently does not have Linux drivers/code available for controllerless PCI modems. However, being that Linux is an open-source operating system, there are many user groups and organizations working on modem projects for Linux. Below are some useful links and resources.
Please note that these sites are not affiliated with or supported by Zoom. All file downloads are entirely at your own risk.
LTModem Drivers for Linux (for Agere/Lucent chipset modems)
Linux drivers for Conexant modem chipsets project