Hi Doug, thank you for answering.
So there are two ways:1) it is possible to build a custom LAN for voice data with a ethernet card connected to PBX and a dedicated hub/switch 2) use my office ethernet LAN used for data and also for VoIP data (mixed)
I looked for a BRI ISDN digium card but I haven't found any, a real pity. There are only some junghanns card but I don't know them....are they good as digium??