Phone call via dock connector

[floridaboater]

Is there a way to have a phone conversation play through the dock connector? I want to charge my phone as I drive and my connector that plugs into the bottom is wired to the car stereo via RCA jacks. Music plays fine, but when I get a call, I have to put the phone up to my ear. Is there a cable that will allow for the phone to work via the dock connector or is the headphone jack my only option?