How do I put modem on existing com

[jan tanjo]

I want to install a modem on a com port that is already there, 98se always want to install a new port on a p3. the two ports that are already there are not being used for anything

[mjc]

What kind of modem is it?

Most software modemds will not install on a real com port, because the software/drivers won't allow it.

But, if you want to have a a chance for it to install on one you'll need to disable both com ports in BIOS.