So it's because her connection is not clear??? You lost me. I need the volume at a decent level to hear...and when I turn it up....hissssssssssssssss. Not really bad but definitely noticeable.Tell the person your talking to to get an iPhone 4, so when they have a 2nd mic, it will clear up the sound quality.
Essentialy, when you turn up the volume on anything, you are amplifying the sound, IE making EVERYTHING louder. So you may not be able to hear an static or noises in the background when you have the volume on normal, but once you turn it up, it also turns up everything else.