Abstract: An intercommunication system for the wireless transmission of speech, employing ternary delta modulation, wherein, for the purpose of asynchronous ternary delta modulation, the delta modulator and demodulator of each subscriber is connected via a modem to either a radio or optical signal channel, respectively, which is common to all subscribers. The modem sends either two high-frequency or optical carriers, respectively, differing by a frequency shift of .DELTA.f to the signal channel only with the +1 or -1 signals, not for the idling state 0, from the delta modulator and is able to receive such carriers from the signal channel in order to decode them as +1 or -1 signals for the delta demodulator.