I found that you must have a transponder; ie ais equipped vhf,ais transponder in order for you to be seen. It is transmitted over the vhf frequency , which one I dont know. It does use the mmsi (Maritime mobile service identity) to identify each individual vessel.I found a lot of info at
Marine Computer Systems Inc. :: MMSI Numbers Demystified
. As far as the DSC (digital selective calling) goes it uses channel 70. So as a result for AIS to work your mmsi number has to be programmed into the radio or transponder.