Activate EMS, be it 911, calling the USCG on the VHF or HF, or whatever. BTW, I'd call
the CG on the radio rather than by phone. I KNOW the radio is going to the watchstander,
and she/he can start the assistance rolling. The phone number might just go to some
public affairs type (but USCG Station Monterey is in the address book in my cell phone
just the same).
So who you gonna call? Ans: it depends. At least in California, cell phone 911 goes
to the highway patrol, who then (if it's not a freeway crash) needs to figure out which
local 911 center to call. If I radio the CG, I know their landline 911 call will go to
Monterey 911. I did transport for an incident off one of the commercial dive boats,
we used the VHF, and the CG had the Monterey ambulance service on the dock when
we got in seven minutes later, and some coasties to handle the lines.
But if I were at, say, Pt. Lobos, I'd probably either call one of the rangers (I have a
couple of their cell phone numbers) or the entrance kiosk, and let them activate EMS.