Carrier telephony and the convergence of voice, data, audio-video and imaging information remain significant cluster market drivers.

The Negative feedback amplifier allowed Bell system to reduce overcrowding of lines and extend its long-distance network by means of carrier telephony.

Pioneer work was carried out on carrier telephony on radio links and for long distance links the 5UCO, an electronic device for the immediate encryption of teleprinter messages was developed.

Various other sets such as the B70 UHF carrier telephony relay, C11/R210 HF transmitter/receiver for Royal Signals use, and the Marconi transmitter D11 and its associated receiver, the R230 were commercial developments adopted as standard sets by the British services.

He also conducted research on ultra-short waves, electronics, and piezoelectric devices, and invented important modulation systems including the constant potential system, the grid modulation system, the rectifier modulation system used in carrier telephony, and the constant-current or Heising modulation system, which was standard on most early radio telephone transceivers.