virtualbox.org

On a notebook with 56k-PCI-modem I have Windows 7 and Windows XP in virtualbox. In W7 the modem is found, but there is no driver available. In virtual XP there is no modem found at all.
Who can explain that?

Explain what? Virtual Machines do not see real hardware.

If the modem is not visible as a comm port then it will not be usable at all.