4 MHz Duplex Channels
| ITU Channel No. |
Coast Transmit kHz |
Ship Transmit kHz |
| 401 |
4357 |
4065 |
| 402 |
4360 |
4068 |
| 403 |
4363 |
4071 |
| 404 |
4366 |
4074 |
| 405 |
4369 |
4077 |
| 406 |
4372 |
4080 |
| 407 |
4375 |
4083 |
| 408 |
4378 |
4086 |
| 409 |
4381 |
4089 |
| 410 |
4384 |
4092 |
| 411 |
4387 |
4095 |
| 412 |
4390 |
4098 |
| 413 |
4393 |
4101 |
| 414 |
4396 |
4104 |
| 415 |
4399 |
4107 |
| 416 |
4402 |
4110 |
| 417 |
4405 |
4113 |
| 418 |
4408 |
4116 |
| 419 |
4411 |
4119 |
| 420 |
4414 |
4122 |
| 421 |
4417 |
4125
(USCG Calling
(See Note below) |
| 422 |
4420 |
4128 |
| 423 |
4423 |
4131 |
| 424 |
4426 |
4134
|
| 425 |
4429 |
4137 |
| 426 |
4432 |
4140 |
| 427 |
4435 |
4143 |
| 428 |
4351 |
(varies) |
| 429 |
4354 |
(varies) |
Note regarding channel 421: 4125 kHz is used for calling, and is for GMDSS distress and safety communications, in the simplex mode. Distress and safety communications have priority over all other communications. The USCG urges that channel 421 not be used in the duplex mode.
| 
