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| on-hook signal; on-hook sign | |||
| сигнал "свободно: 50 phrases in 16 subjects |
| American usage, not spelling | 1 |
| Astronautics | 2 |
| Communications | 1 |
| Electronics | 2 |
| Makarov | 3 |
| Mass media | 8 |
| Medical | 3 |
| Medical appliances | 1 |
| Microelectronics | 1 |
| Military | 2 |
| Radiology | 1 |
| Rail transport | 13 |
| Spectroscopy | 2 |
| Technology | 3 |
| Telecommunications | 2 |
| Telephony | 5 |