Using Windows 98/2000 it is not possible to share a single sound card with multiple applications. For example, it is not possible to run MMTTY and IP-Sound at the same time using a single card, only one application will run and the other will fail to open the sound card. Sharing a sound card is possible under Windows XP and 2003. For my Windows 2000 server this was a problem.
Enter Wave Clone. Installing this software allows the sound card to be shared by several applications under Windows 98 or Windows 2000. For me this allowed me to run MMTTY and IP-sound at the same time using a single sound card under Windows 2000.