Re: Vhf Radio.
You will need to register [a VHF Marine Band radio with digital selective calling features] to use the red button feature.
I am certain the advice given was not intended to be misleading, but unfortunately it is. When you buy a VHF Marine Band radio for use with a voluntary-equipped vessel in the United States, you do not need a station or operator's license, nor do you need to register the radio with anyone. Nor is the radio registered in any way with an agency involved with search and rescue. What was probably intended to be conveyed to you was this:
Radios with DSC features identify themselves with a marine mobile service identity or MMSI. To use a DSC radio you simply program the radio--yourself--with your vessel's MMSI. The MMSI is associated with the vessel, not with the radio. It is the vessel which is registered in the MMSI database, not the radio. A vessel could have several radios, and they all would use the same MMSI. When you register your vessel to obtain an MMSI, no information is needed about the radio.
A radio with digital selective calling features cannot use those features until it has been programmed with an MMSI. Thus all DSC radios that are making use of their DSC features have been programmed by their owners with the MMSI of the vessel where they are used.
If the radio has already been registered you may have to have the old owner "release: the radio from his registration. MSSI is the name for the unique identifier.
Again, here the intention was probably to offer advice about a radio that has already been programmed with an MMSI. Again, the radio itself is not registered in any way.
Also, the identifier is the MMSI, not the MSSI as mentioned above. The marine mobile service identifier follows the vessel, not the radio. Therefore, you do not take over an MMSI when you get a radio. The MMSI is associated with a vessel, not with a radio.
In the design of the digital selective calling system, a DSC radio must prevent the operator from capriciously changing the MMSI associated with the radio. The thinking behind this was probably intended to prevent radios from easily being changed to impersonate other vessels. This reduces the opportunity for hoax digital selective calls. As a result, once a DSC radio has been programmed with an MMSI, it cannot be altered by the end user of the radio. However, if you return the radio to the manufacturer, the manufacturer can reprogram the radio with a different MMSI. Generally this service is available for a modest fee, or in some cases at no charge; it depends on the manufacturer of the radio.
Early DSC radios allowed the MMSI to be programmed twice. If you have such a radio and it has only been programmed once, you may be able to alter the MMSI programmed into the radio yourself. Newer radios, however, tend to only permit one MMSI entry and then must be returned to the manufacturer if a new MMSI is to be entered.
A further clarification regarding the position information: the radio will be glad to transmit whatever position you would like to enter into it. The position does not have to come from a GPS receiver. You can enter the position manually, however that is awkward and rarely done. More common--practically universal--is to connect the DSC radio to some electronic device which supplies the vessel's position. On small boats this is almost always a GPS receiver.
