Using more than 1 modem with Windows 2003's fax service

Hello,

one of our customers currently uses a Windows 2003 (SBS) for sending out
faxes. For this there's a AVM Fritz!Card PCI installed, which - what is a
known issue - does not work very well with Windows 2003. Unforunately, the
server does not support "old" 5V PCI cards, only PCI-X or 3.3V PCI, so the
alternative AVM B1 and other do not work either.

So we had the idea of just installing a fax-modem PCI card, which should
work fine for this customer. But: He sometimes needs to send a large number
of faxes, so he must be able to use multiplne (ISDN) channels
simultaneously. Is this possible with Windows 2003's fax service? I heard of
some issues with multiple modem cards where fax service sees only one of
them (when they have the same name?!)? Of course the fax modems can be
connected to a telephone system with enough free lines.

Best regards,
Tobias