a communication device configured to performing communication with an external device . the communication device includes a calculation unit , a recording unit configured to record a first firmware that makes the calculation unit function in a first mode , and a second firmware that makes the calculation unit function in a second mode that is different from the first mode , and a communication unit , when the calculation unit receives a signal from the external device in a designated state switching from execution of the first firmware to execution of the second firmware , configured to make a response not according to contents of the received signal .