In car speakerphone with EVO mic

[adenicol]

I have an FM transmitter that I use in my can so I can listen to streaming audio (ex: pandora) on my car's radio. The FM transmitter plugs into the headphone jack on my EVO.

The problem I have is when I get a call I have to unplug the headphone cord and then answer the phone.

Is there anyway possible to answer the phone while it is still connected to the FM Transmitter and use the car's speakers for the call while using the EVO's microphone to talk? The problem I see is that if there is something plugged into the headphone jack, it seems like the phone's mic is not enabled.

Anyone have any ideas?