I had spotty Bluetooth connectivity and talked with a Tesla service rep (Zander), who recommended that I recycle the power to the entire car, then reset the touchscreen, then re-pair my phone. That fixed the problem. To reset the power to the entire car, go to Controls > Safety and hit the Power Off button. Let the car power down and leave the power off for 2 minutes. Then hit the brake pedal to turn the car back on. To reset the touchscreen, push down both buttons on the steering wheel. To re-pair my phone, go to Bluetooth on the touchscreen, forget my phone, and go to Settings > Bluetooth on my iPhone to forget the Tesla. Then re-pair the phone to the Tesla.