A device for making efficient use of the free time between speech transmissions and binary coded data transmissions, the device including a switch which will automatically output both the binary coded data and the outgoing speech signals to a telephone line and which will connect to the device, each of the incoming signals received from the telephone line. The device includes an outgoing transmission block and an incoming transmission block. The outgoing transmission block outputs speech signals or data signals selectively after mixing the signals with one of two tone signals of different frequencies. The incoming transmission block first identifies incoming signals by two bandpass filters and then, depending on the identity of the signals, selectively connects the incoming signals either to a speech restoration circuit or to a data restoration circuit.