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VHF Marine Radio Digital Selective Calling | What is it?

What is Digital Selective Calling (DSC)?

DSC is a semi-automated means of establishing initial contact between stations. Once contact has been made, communications on a nominated HF frequency or VHF voice channel should be used to pass messages.

What is the status of DSC coverage in Australia?

The Australian Maritime Safety Authority is responsible for the maintenance of an HF DSC capability in Australia for shipping, meeting the requirements for operating under the Global Maritime Distress and Safety System (GMDSS). Other vessels with HF DSC equipment may also use the service for distress alerting and, if they meet the criteria, position reporting. In Australian waters, VHF DSC is for ship-to-ship alerting. There is no official shore-based infrastructure but there are a number of volunteer marine rescue (VMR) stations that have installed VHF DSC and a check with your local VMR should be made.

VHF DSC for small craft is primarily for distress, urgency and safety purposes.

How should VHF DSC be used?

In Australian waters, Channel 70 should be used for DSC distress alerts only. Once an alert has been sent the party in distress should monitor Channel 16, the distress and calling channel. Parties receiving the DSC distress alert should switch to Channel 16 and acknowledge the MAYDAY call by voice giving their identity and signalling “Received MAYDAY”. If the party in distress does not receive an acknowledgement to their DCS alert they should transmit the standard MAYDAY call by voice on Channel 16. There are still quite a number of boats that do not carry DSC radios.

Because Channel 16 is the distress and calling frequency it should only be used for general traffic to raise another party. Once contact has been made, all routine traffic should be passed on another agreed VHF channel.

Is a call sign or Maritime Mobile Service Identity (MMSI) needed?

An MMSI is a unique nine-digit code set into your DSC terminal to identify your vessel. You need only one of these if you have multiple DSC radios. You use the same MMSI for all radios on board the one vessel as it is a ship’s identity. Because VHF radios now operate under a Class License there is no requirement for an official call sign but an operator must have a Maritime radio Operators Certificate of Proficiency (MROCP).

How can a MMSI be applied for?

The Australian Maritime Safety Authority allocates MMSI. To apply for an MMSI complete the MMIS Application form available for download via This page has important information about MMSI and DSC radio.

What qualifications are needed to operate an HF or VHF DSC radio?

The minimum qualification to operate a VHF radio with or without DSC is a Marine Radio Operator’s VHF Certificate of Proficiency (MROVCP). VHF radios are covered by a Class License so an individual station license is no longer required.

The minimum qualification to operate an HF radio with or without DSC is a Marine Radio Operator’s Certificate of Proficiency (MROCP). HF radios need to be individually licensed with the Australian Communications and Media Authority, who also allocate Australian radio call signs.

Where can I purchase a handbook?

The Marine Radio Operator’s Handbook produced by the Australian Maritime College provides further information about qualifications, licensing and DSC operations.

It is available at

Print out Fact Sheet courtesy of AMSA:

Rescue Coordination Centre (RCC)-Australia
24 hour emergency contact telephone number: 1800 641 792
General enquiries during business hours: 1800 406 406

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