Source: americanboating.org & Navigation Center of the U.S. Coast Guard

Although telecommunications technology is improving quickly, people at sea do not have access to the same telecommunications infrastructure people ashore have. Like people ashore, mariners need to access international shore telephone and data public switched networks. Additionally they need to access many maritime specific communications listed below:

• Mariners need to be able to communicate with other ships of any size or nationality.
• Mariners need to be able to receive and send urgent maritime safety information.
• Mariners need to be able to send or receive distress alerts in an emergency to or from rescue coordination centers ashore and nearby ships anywhere in the world.

Maritime telecommunications systems must be internationally interoperable. Bringing new telecommunications technology to mariners can be difficult, since to be interoperable, the technology must be affordable, acceptable and available to most ships and maritime countries.

The Coast Guard does not advocate cellular telephones as substitute for the regular maritime radio distress and safety systems recognized by the Federal Communications Commission and the International Radio Regulations — particularly VHF maritime radio. However, cellular phones can have a place on board as an added measure of safety.

Cellular Phone Limitations in an Emergency

• Cellular phones generally cannot provide ship to ship safety communications or communications with rescue make a distress call on a cellular phone, only the one party you call will be able to hear you.
• Most cellular phones are designed for a land-based service. Their coverage offshore is limited, and may change without notice.
• Locating a cellular caller is hard to do.  If you don’t know precisely where you are, the Coast Guard will have difficulty finding your location on the water.