Bluetooth setup with my Droid2 (Verizon) has never been a problem. When I'm in the car, incoming calls are received perfectly, and calls that I make through the phone itself are immediately picked up by the vehicle's bluetooth.
Placing hands-free calls, though, is sketchy. The most frequently occurring problem is an inability to complete a call the voice recognition/hands free system initiates. I hear it "dialing" but, after about 5 seconds, the speedometer console advises me the dialup failed. If I repeat the process, the call goes through successfully.
All told, this happens about 50% of the time.
With the support and assistance of VW of America, my bluetooth unit was replaced. The problem recurred.
I tested the bluetooth setup with an old, "basic" phone and everything is rock solid. The difficulty seems specific to the Droid 2 (with the latest Android system, 2.38 (I believe)).
I'm new to Android, but my OS is at 4. I realize that not all Androids can get the latest update, but anything on v2 seems old. Also check the firmware on your phone.
I would look around to see if there's a custom ROM for Jelly Bean available for your phone. Android 2.xx has been out for years and is obsolete.
Other than that, if the bluetooth radio was replaced in your car and the problem persists yet it works with another phone I would start wondering if your phone has a defective bluetooth radio.