Tony,
According to the
HP website, that PC had the V90 modem as a PCI card, rather than on the MoBo. It is possible that someone added another PCI modem card, Fax card, or even an ISDN card.
The only connectors on the mobo are:
1 - Mouse
2 - USB
3 - Parallel
4 - Gameport
5 - Microphone
6 - Line-in
7 - Speaker out
8 - Serial
9 - Keyboard
Anything else is in a PCI slot.
SD