As PVJ stated Executone willl not work on Nortel system.
The OPXI converts a digital port to an analogue port, for use with fax, cordless phone, etc.

It depends on which Nortel system you have? Option or Norstar


If Norstar CICS, there is one built in. If ny other Norstr, you need an analogue adapter or analogue station module.

If option, you need a analouge station card.

If all else fails, use a BFH.