Aux-in with Iphone 3G

[dipdog]

Hi. Like a lot of folk, I've been trying to find a car charger/aux-in that will work for my Iphone 3G. I've seen the compatibility lists, and I've found some chargers with aux-in that work. The best sound that I got was from the Griffin Autopilot. My question is, even though the charger function works with the 3G on several of these chargers, and the aux-in works when playing music on the 3G using these same chargers, I've noticed that when you make a phone call, the sound no longer comes out of the car speakers. This is confusing because when I have the car speakers connected (via cassette adapter or direct line-in) to the earbud jack on the Iphone, both the music and the phone functions come through the car speakers. But when I use the aux-in on a car charger, only the music comes through (not the phone - if I make a call, the music in the car speakers fades and the phone sounds come out of the phone).

Did the original Iphone work this way? It's disappointing because I'd like to avoid the hassle of having two connectors (one to the earbud minijack and one to the charger) but I also like having the option to use the phone over the car speakers. Has anyone else noticed this, or are there any car chargers with aux-in that play both music and phone? Is this a function that will likely work when Apple releases new branded accessories?

Thanks for your input!

[MBHockey]

I couldn't find an accessory that worked this way, so I bit the bullet and got a Plantronics 925 headset from newegg for half of its crazy $150 retail price.