I've replaced the factory in-dash stereo receivers in my personal truck and my work truck with aftermarket units that include Bluetooth. I put a nice one in the personal truck, a JVC that cost over $200. The one in the work truck has less features, it's an Alpine that cost around $130.
Both units have little microphones that mount near the sun visor. The call audio is played thru the stereo speakers. For the most part they both work great. I purchased from Crutchfield. They're a great online retailer but I'm fortunate to live near their two retail stores.
The stereo's automatically sync to my phone when I get in and turn the truck on. When a call comes in it mutes the stereo and plays the ringer thru the speakers. You hit a button to answer, have you call, and then, when the caller hangs up the stereo goes back to playing music. It's great.