I've noticed a glitch between my B&W p5 headphones and my 16gb iP4. While on a TTY call using the headphones, the headphone volume defaults to max and I can't control it using the buttons on the headphones OR on the iPhone. In order to adjust the volume, I have to unplug the headphones from the phone, then manually change the volume using the buttons on the phone. I haven't tried this yet with the stock apple headphones. I'm curious if anyone else has noticed this issue. The headphones work properly using the iPod app, sirius, pandora, etc....It seems to be limited only to TTY calling.