Not always but usually. This really should not be an issue in the San Francisco / San Jose area with overlap. Sure tunnels, remote areas and a few rare occasions of dead areas are expected to drop calls. You expect limitations on the technology; however, these are network overload call drops. Time of day is a major factor and as the popularity of the iPhone grew so did the dropped calls. Then the addition of SMS which was held off for a reason came along and poor service areas became ridiculously poor.