A communication method is a communication method for communicating between first device and second device over one of first network and second network, and includes transmitting a common identifier from the first device to the second device over one of the first network and the second network, the common identifier being for uniquely specifying the first device in both the first network and the second network, receiving the common identifier at the second device, and communicating between the first device and the second device over one of the first network and the second network.