I'm having the same problem as well and another annoying thing too.
I use the headphone jack on the phone to plug into my deck in my car for listening to music. But as soon as I take or make a call and then hang up it disconnects from the headphone jack and outputs the music audio through the phone speaker. The only way I've figured out to get the audio back through the headphone jack is to unplug it and plug it back in. This is a little difficult to do while driving down the road and annoying as hell. My iphone never had this problem.