ISDN dialin

hi all, we were planning to setup a dailin server with multiple isdn cards, of type: Eicon Diehl Diva 2.0 PCI BRI and AVM A1 cards it should be possible to use several of the B-channels at the same time, unfortunately, there is some rumour going around, that zou can use only one card at a time (as in: one connection at a time) the rumour was, that this is some sort of a hardware? limitation. can somebody shine some light on this matter, and/or if its true, suggest cards, that are *known* and tested to work in multicard configs? thanks already in advance, Alex