Modem default Com4

My sister’s modem, an ISA 28.8k modem recently went to hardware heaven after I defragged the system as well as for some reason losing my brother-in-laws files which he had in the “My Docs” folder and didn’t back-up.
I went to the computer show andpurchased a Wincomm 56k which installed fine, however, it defaults to Com 4 which is not recognized. I went to the Bios to try to change the settings as well as under the Device drivers and resource settings to no avail.
Do you have any suggestions? I am drawing a blank to a situation which is probably quite obvious.
Thank you,
Cybercop