An aftermarket, sound activated, wireless, vehicle door unlocking device comprising a sound sensor, processor, memory, and an RF transmitter, transponder, or transceiver capable of generating an unlocking signal, and method of using the device. The device may be easily installed by unskilled users without modifying the vehicle wires or structure. The operator of the device will program the device with an unlocking sound sequence, and the RF unlocking codes needed to unlock the vehicle door. The device continually monitors the sensor for unlocking sounds, and delivers a door unlocking signal when this sound is detected. Various embodiments, including embedded RF key embodiments, solar powered embodiments, and alternative ways of programming the device are also discussed.