Programming a PBX with a laptop
 

Might be of help for anyone getting hold of one of the older Panasonic KXTD SERIES
This just came to mind ,when looking at an old Panasonic KXTD lap top program. For some time I had problems on an old laptop connecting to these ( KXTD 1232/816) using the maker's program, and Panasonic at time had no solution.
I found by trial and error that the default IRQ set in the program, may be in conflict with that set up in the laptop. Change IRQ and laptop talks to switch. Might work for other makes of switch that can be programmed using makers software.