Originally Posted by Classic30
...Having DSC on the radio is obvious, but having AIS on the VHF, even without GPS, allows push-button "target calling" - not something you can do from a chartplotter.
A couple clarifications here:
Whether your radio has AIS or not, you really should connect a GPS to it (either a chartplotter or, if you don't have that, get a puck like the Garmin 18x LVC). With GPS connected, any DSC calls will transmit your location, including (especially) distress calls that you place with the panic button. It's an important safety feature.
Also, for those who have VHF/AIS combination radios, feeding GPS has the added benefit of enabling the radio to prioritize the AIS targets from closest to farthest, which greatly helps in crowded areas. The GX2100/2150 also have a rudimentary graphical display that shows the targets on your screen, and allows you to select which boat to query or call. But that also requires the GPS signal because it needs to know where your boat is relative to the other AIS targets.