TELECOMMUNICATIONS (ELECTRICAL), TELEGRAPHY, TELEPHONY, RADIOCOMMUNICATIONS, TELEVISION, VIDEO ENGINEERING, TELECONTROL

DIGITAL TELEPHONY + DIGITAL TELEPHONE ENGINEERING (TELECOMMUNICATIONS)

TELEPHONE APPLICATIONS (TELEPHONY)

LONG-DISTANCE TELEPHONY (TELEPHONY)

MULTIPLE TELEPHONY (TELEPHONY)

PUBLIC TELEPHONE SYSTEMS, AUTOMATIC EXCHANGE, SWITCHING SYSTEMS, SIGNAL TRANSMISSIONS (TELEPHONY)

PRIVATE TELEPHONE STATIONS + PRIVATE TELEPHONE NETWORKS (TELEPHONY)

ELECTRIC CIRCUITS + SWITCHING CIRCUITS (TELEPHONY)

TELEPHONE INSTALLATIONS, TELEPHONE STATIONS, EXCHANGERS, NETWORKS (TELEPHONY)

TELEPHONE APPARATUS, TELEPHONE RECEIVERS, CALLING APPARATUS, TRANSMISSIONS AND SUPERVISING EQUIPMENTS (TELEPHONY)

WIRELESS TELEPHONY + MOBILE TELEPHONY (RADIO ENGINEERING)

MOBILE RADIOTELEPHONE (RADIO ENGINEERING)

MOBILE COMMUNICATIONS + CELLULAR COMMUNICATIONS (RADIO COMMUNICATIONS)