The GMDSS provides that every ship, while at sea, shall be able to perform the following nine basic communication functions: transmitting ship-to-shore distress alerts (by at least two separate and independent methods); that every GMDSS equipped ship shall be capable of:
receiving shore-to-ship distress alerts;
transmitting and receiving ship-to-ship distress alerts;
transmitting and receiving search and rescue co-ordinating communications;
transmitting and receiving on-scene communications;
transmitting and receiving signals for locating;
transmitting and receiving maritime safety information;
transmitting and receiving general communications; and
transmitting and receiving bridge-to-bridge communications.