also the PM14400 PS/2 Internal Modem and Kingston 14400 PS/2 Internal Modem
193-382 IBM PS/2 14.4KBPS DATA/FAX MODEM ADAPTER/A
Intmod14.exe 14.4 Modem w/Wake-On-Ring option disk (adf only!)
Wake on ring feature seems to be a rework. There is an IC that looks to have been snapped in half and glued upside down onto U18. Two wires run from the added IC segment, one to R54, the other to the left pin of the header P2.
I dimly remember someone saying it was an option for the 750
MCA/PCI systems and not likely to be useful to any earlier ones.