I use a Parrot Evolution BT module, with the microphone in the OEM factory (steering column) mic enclosure. I have it wired to the head unit with a Connects2 harness so it works with the steering wheel controls for OEM functions like call originate/answer, hangup, redial, and volume.
My BT phone is an iPhone 4S that is wired through a Mediabridge 1500 to the head unit via the CD changer connections, but your Galaxy should work fine through the AUX head unit connection. The hardwired dock connection I have through the Mediabridge additionally charges the phone and displays music info on the HU.
I don't use the Parrot's contacts directory, or built-in voice commands. I use the phone's contacts and Siri voice control (via the steering wheel phone buttons) to dial and receive calls, send/receive and read texts, get weather, set reminders, control music, request turn-by-turn GPS navigation, etc. The Parrot mutes the music automatically (regardless of source - FM, AUX, CD, Mediabridge/iphone) for incoming calls, or when voice control is used via the 'talk' button on the steering wheel.
The Mediabridge actually has BT capability for both phone and streaming audio, but I don't use them. It doesn't allow for full use of the OEM steering wheel controls, can only receive calls /mute etc. when the head unit is on the Mediabridge input. I also like the wired audio quality via direct connection.
This setup works perfectly for me - the phone is a lot smarter than the factory media/phone solution ever was, and the manufacturer keeps upgrading the firmware to add more features ...
