Q: If my iPhone 3G is playing music through my car stereo connected via a mini stereo cable to the stereo’s auxiliary jack, will I still be able to receive phone calls on my Bluetooth headset or handsfree device in the car? What will happen when I receive a call while music is playing?
A: The iPhone music playback and phone audio are handled separately in this case, so you can easily listen to your iPhone music through the headphone jack or a Dock Connector based audio accessory and continue to use your Bluetooth headset or handsfree accessory to make and receive phone calls.
When a call comes in, the music will fade down and the iPhone will ring as it normally would. Answering the incoming call from your Bluetooth headset or handsfree kit will route the phone call audio through the Bluetooth accessory and the music will remain paused while the call is in progress. When you hang up the iPhone will automatically resume playback by fading the music back up to its previous volume.
Note that if you answer the call from the iPhone screen itself, the call audio will not be sent to your Bluetooth accessory by default, but will use the iPhone’s audio input and output, meaning that you will likely hear the call audio through your stereo speakers and the iPhone mic will be used to pick up your voice.
The same process also occurs when dialing an outbound call from the iPhone. You do not need to pause your music playback before making a call—simply place the call and the iPhone will fade down and pause the music while your call is in progress.
For more information on how this all works, be sure to check out our Complete Guide to iPhone Car Integration.