Acer-help!

I have an Acer laptop with Windows XP. I've been trying to do a video call with my friend that is overseas, but it keep saying the acer isn't compatible with their microphone. I can see them just fine, but we can't talk back and forth through our mics. Is there a driver or something I need? Can anyone help me? If so, please e-mail at [email protected] as soon as possible!!