I am on a fringe area, even though both ATT (Tesla) and Verizon(my phone) say I should have no signal issues. I notice my WiFi (Cell over WiFI) phone will not connect to the car until the car can connect to ATT, even though the car is also connected to my WiFi. I think it requires the ATT connection to be good enough to maintain Tesla secure connections. When I leave my home, the car takes several miles until it can connect, and when at home it sometimes loses connection. When you are near the car, bluetooth may enable you to unlock the car.