Abstract: A system prevents operation of a land vehicle having an interior when a communication functionality of a mobile phone is in use within the interior. The system includes a power source and a dual-mode mobile phone disabler including a processor powered by the power source and an antenna operably connected to the processor. Before the vehicle is on, the antenna detects a communication signal from the mobile phone within the interior when the communication functionality including communication with a cell site is in use. In response, the processor prevents the vehicle from being turned on until the antenna detects no use of the communication functionality. The communication signal indicates use of the communication functionality. After the vehicle is on, the processor, via the antenna, periodically communicates with the mobile phone within the interior to keep disabled the communication functionality. When the vehicle is off, the antenna ceases to communicate.