A relaying device includes a wireless apparatus interface, a signal processing unit connected to the wireless apparatus interface, a network interface, and a packet processing unit connected to the network interface. The relaying device is provided with multiple communication paths including the wireless apparatus interface, the signal processing unit, and the packet processing unit, and each communication path has a mixing unit configured to additively synthesize an uplink audio signal and a downlink audio signal of other communication path to the uplink audio signal and input the synthesized signal to the packet processing unit, and configured to additively synthesize an uplink audio signal and a downlink audio signal of other communication path to the downlink audio signal and input the synthesized signal to the signal processing unit.