Change system resources for modem in xp

Hi,
I have a very old pc in my shop. I could not get the pc to pick up a dial tone. I tried 2 different modems with the same results. The client wanted xp even though the system did not meet min requirements. The pc has com 1 and com2. The creative Di5652-1 is installed and the irq is 10 and attached to com 3. How do I change the resource to use either com 1 or com 2. I look in modem properties and it is all greyed out and I cannot change the resources. No matter where I have looked it is the same. I did a clean install full version xp home and it still finds com 3.