The HP iPAQ 910c (and maybe other iPAQ's on that series) can lose audio from the device's speaker if you hang up a phone call using the button on a Bluetooth headset. The most obvious way to get audio working again is to soft reset the device, but that is not needed! Until HP decides to fix the problem (if they ever do), here's how to get audio working again without soft resetting the phone.
1. Go to Start menu, Settings, Phone.
2. Set Keypad to Short Tones (HP made "Off" the default option) and press the OK button.
3. Go back to the Today screen and dial a couple of digits, then press the phone hang-up (the red phone) key.
Audio will be operational again. From now on, every time you get this problem, you just dial a couple of digits then press the hang-up key and you are back to business.
