Problem with mircophone

[kimp]

I have a problem with the sound when using my mircophone to make calls via the internet. I have adjusted the volume on my system as well as on my headset but as soon as I connect in the call the volume for the mircophone turns itself way down. This is on the settings for Audio in Windows XP with SP2. I try to turn it back up but it will not move it is greyed out. I need help cause it is very hard to hear the other person speak and I have to put the mircophone very close to my mouth. Please help. Thanks