Connecting to an AUX input device

This seems like the appropriate area to ask this question.

So with the 3.5mm headphone jack, it will obviously work with external devices that have an AUX input available, such as when connecting and MP3 to your vehicle.  So with that said, can I simply connect my Touch (that I won't own for about 48 hours  ) to my AUX input and play the music through my car stereo?  How will it know I'm not just using headphones (4 amplified headphones)?  And while on the topic, even if I were not playing music would I be able to listen to a caller through my car's speakers?  Again, how does it know I don't just have headphones plugged in.  I would have to initiate speaker phone mode for it to pick up the mic which could inturn disable the earphone jack I suppose.  I'll know soon enough if nobody here has tried that.  Blackberry Storm works that way I'm told.  It almost seems to me that when the 3.5mm jack is being utilized the mic would be activated and speakerphone disabled and redirected to the AUX device.

Good point...never thought about the fact the mic terminal is connected also.  Duh!

I know the Blackberry functions as I mentioned, I'm hoping I can also use the AUX input in my truck to play music (once I actually get mp3's - I am muscially challenged) and have it double as an external speaker when connected.

Thanks for the reply.  Kinda needed a bonk to the forehead on that one.

Yeah, that's my post as well.....I was answering another.  There is bound to be similar topic threads since most threads end up getting hijacked.

That's because the microphone is disabled when headphones are plugged in. A message usually pops up on the screen telling you this when you plug in a set of headphones.

I actually began this post prior to my purchase with hopes it would work as the Storm does.  Once I made the purchase and experimented I found it will not work, and yes it does warn you the headphone has no mic jack.  It's unfortunate.  It's not really designed for that type of use anyway.

I concur =P I usually try and minimize driving distractions.
It was cool but slightly annoying to hear that our phones had 3.5mm jacks. I like the versatility, but I really don't want to spend the extra money to get a good 3.5mm headset! I just want to use the one I already have haha.
Hopefully you get your dilemma sorted out. Listening to someone talk on the car's speakers would be nice, but I'm sure bluetooth or even just a simple headset would work just fine.