Modem Configuration requires familiarity with both the specific OS and the specific modem being used.
While the following procedure is sufficient for most cases, it may be necessary to take additional steps to properly configure your modem or to set up the OS for a specific application. 

1) The Cable

Use a straight through Modem Cable as found via the Cable Selector on the Digi Support page.

2) The Linux Server

NOTE: This step requires that the "uucp" package be installed.

chown uucp:uucp /dev/[ttyid]*

Example for RAS/Xp devices:

chown uucp:uucp /dev/ttyG*

Example for AccelePort Xem devices:

chown uucp:uucp /dev/ttyD*

*NOTE: Only use the altpin setting if you are using 8-wire (non-digi) cables on your modem. On PortServer and Digi One products, this is set on the units themselves.

Possible error messages when doing the step 2, above: 

getty respawning too rapidly -- check /etc/inittab file for errors.