IPhone default Bluetooth music app

The app you are referring to has a manual process you can try, but it is not for the faint of heart: http://blog.ramondeklein.nl/?p=257

Howto disable A2DP on the iPhone

The interesting directory is /var/mobile/Library/Preferences, where the iPhone stores the BlueTooth settings. These settings are stored in the PLIST format, so you need a PLIST editor (Mac or PC) or you need to convert them by hand. Transfer the com.apple.MobileBluetooth.services.plist to your computer or you can use iFile to edit the file on your iPhone directly.

Open the com.apple.MobileBluetooth.services.plist in your PLIST editor and make sure you edit the A2DPService section and store the devices you don’t want to use A2DP in the UnauthorizeList (without the letter “d”). This dictionary will probably not exist yet, so you need to add it by hand. You need to know the MAC address, but it is probably listed already in this file.

<key>A2DPService</key>
<dict>
  <key>State</key>
  <true/>
  <key>UnauthorizeList</key>
  <dict>
    <key>00:10:60:D0:91:D0</key>        <!-- This is the MAC address -->
    <date>2009-08-08T01:00:00Z</date>   <!-- Timestamp -->
  </dict>
</dict>

Transfer the PLIST file back to your iPhone and reboot the device. Once it gets back on, then the A2DP service should be disabled.

On a jailbroken iPhone, with SBProfiles and SBSettings you can utilise profiles to group multiple actions to different situations. The downside is that you have to manually switch the profiles when entering and leaving the car.

1. Make sure you have SBProfiles and SBSettings installed from Cydia.

2. Open SBProfiles. It should have multiple profiles by default; Default and Car among them. Select Car and then Toggles. Drag Airplane and Bluetooth to On section. Make sure that Airplane is on top of Bluetooth, otherwise activation of Airplane will turn Bluetooth back off.

3. Then, go back to Car and select Done from the top bar. Select Default and then Toggles. Drag Airplane to Off section (and Bluetooth, if you don't need it outside the car).

4. Select Settings from the bottom tabs. Select Activation Method(s) under Profile Switching. Here you can select the action(s) that trigger the profile selection to become active. I think it defaults to Short Hold of the Sleep Button.

Now, when you hold the Sleep Button a bit longer than shutting down the screen but not long enough to power off the iPhone, you can select Car profile and have cellular turned on but Bluetooth on. Or select Default to turn cellular back on. I think you will have to make the call still, unless there's a way to automate it, too.