| 33020 | Telecommunications in general |
| 33030 | Telecommunication services. Applications |
| 33040 | Telecommunication systems |
| 33050 | Telecommunication terminal equipment |
| 33060 | Radiocommunications |
| 33070 | Mobile services |
| 33080 | Integrated Services Digital Network (ISDN) |
| 33100 | Electromagnetic compatibility (EMC) |
| 33120 | Components and accessories for telecommunications equipment |
| 33140 | Special measuring equipment for use in telecommunications |
| 33160 | Audio |
| 33170 | Television and radio broadcasting |
| 33180 | Fibre optic communications |
| 33200 | Telecontrol. Telemetering |
