Most vehicles when using CarPlay, will disconnect from Bluetooth, since you have to plug the iPhone into the USB connection in the vehicle. This will disconnect the vehicle from Bluetooth, however you should still be able to make calls through CarPlay when you tap on the Phone icon. If not, then it would make me wonder how CarPlay is programmed for your vehicle. When plugged into your vehicle, your controls in the vehicle should still function and allow you to use the phone for calls, messaging and other functions. If not, check with your vehicle manufacturer to help you troubleshoot this problem.