bluetooth headset won't override wired jack (GSM only)

[brett]

To get more visibility on this question,
I am putting a copy of this in the bluetooth section too.

I have a GSM Treo with the wired jack connected to the AUX in on my car stereo for playing of Audiobooks via Audible and MP3s.

I would like to use a Bluetooth headset to make and receive calls.
So when a call comes in, I would like it to pause my audiobook/music and re-route the audio to the Bluetooth headset so I can take the call, then when I am done the audio should be routed back to the wired jack so I can continue listening to my book/music.

Apparently this works fine with CDMA Treos, the issue only appears to be present on GSM models.

Is there a software patch, or a software program available to fix this issue on GSM Treos?

Thanks

-Brett