for a bit more clearety :
No,
yes you have power from your ISDN provider but u whont hevane power to convert the analoge to your ISDN card to put it on ISDN (if power fail)
Posabilety solution : 1 separate ISDN phone who got the power from the ISDN box provider ( so an line to the place for an imergancy phone on an seperate ISDN number)
else the phone rings seperate to your PBX system (at least in NL you got 2 ISDN outputs on 1 box)
Cheers,
Panasonic TDA/TDE/NCP/NS Series