The Maritime Mobile Service Q Codes are art of a larger set of Q Codes designated by the ITU-R. The QOA–QQZ code range is reserved for the Maritime Mobile Service.
This assignment is specified in RECOMMENDATION ITU-R M.1172.
Q signals are no longer substantially used in the maritime service. Morse code is now very rarely used for maritime communications, but in isolated maritime regions like Antarctica and the South Pacific the use of Q Codes continues. Q Codes still work when HF voice circuits are not possible due to atmospherics and the nearest vessel is one ionospheric hop away.
From ITU Radio Regulations 1990, Appendix 14: Miscellaneous Abbreviations and Signals to Be Used for Radiocommunications in the Maritime Mobile Service.
| Question ? | Answer or Advice | ||
|---|---|---|---|
| QOA | Can you communicate by radiotelegraphy (500 kHz)? | I can communicate by radiotelegraphy (500 kHz). | |
| QOB | Can you communicate by radiotelephony (2182 kHz)? | I can communicate by radiotelephony (2182 kHz). | |
| QOC | Can you communicate by radiotelephony (channel 16 - frequency 156.80 MHz)? | I can communicate by radiotelephony (channel 16 - frequency 156.80 MHz). | |
| QOD | Can you communicate with me in ... 0. Dutch 5. Italian 1. English 6. Japanese 2. French 7. Norwegian 3. German 8. Russian 4. Greek 9. Spanish? | I can communicate with you in ... 0. Dutch 5. Italian 1. English 6. Japanese 2. French 7. Norwegian 3. German 8. Russian 4. Greek 9. Spanish. | |
| QOE | Have you received the safety signal sent by ... (name and/or call sign)? | I have received the safety signal sent by ... (name and/or call sign). | |
| QOF | What is the commercial quality of my signals? | The quality of your signals is ... 1. not commercial 2. marginally commercial 3. commercial. | |
| QOG | How many tapes have you to send? | I have ... tapes to send. | |
| QOH | Shall I send a phasing signal for ... seconds? | Send a phasing signal for ... seconds. | |
| QOI | Shall I send my tape? | Send your tape. | |
| QOJ | Will you listen on ... kHz (or MHz) for signals of emergency position-indicating radio beacons? | I am listening on ... kHz (or MHz) for signals of emergency position-indicating radio beacons. | |
| QOK | Have you received the signals of an emergency position-indicating radio beacon on ... kHz (or MHz)? | I have received the signals of an emergency position-indicating radiobeacon on ... kHz (or MHz). | |
| QOL | Is your vessel fitted for reception of selective calls? If so, what is your selective call number or signal? | My vessel is fitted for the reception of selective calls. My selective call number or signal is ... | |
| QOM | On what frequencies can your vessel be reached by a selective call? | My vessel can be reached by a selective call on the following frequency/ies ... (periods of time to be added if necessary). | |
| QOO | Can you send on any working frequency? | I can send on any working frequency. | |
| QOT | Do you hear my call; what is the approximate delay in minutes before we may exchange traffic? | I hear your call; the approximate delay is ... minutes. |