Yes, SPOT uses its GPS for position and then sends the position over the
Iridium network. I'm not familiar with the Sat phones and it never crossed
my mind that they would provide position information. According to Zac's
parents, the Iridium rep told them that they can determine position from the
call records and this information is often used for SAR.

It was the far off course position that put Zac in a dangerous area that
panicked his parents, not just the silence. Possibly a units mix up as you
say but Zac's parents are professional yacht delivery people so it doesn't
seem highly likely. Sound like Iridium indirectly determines position in
some fashion that can be plotted by them but not the user. It would be
consistent for the information to be useful to SAR when no other position
information was available but approximate or error prone enough that it
could show Zac off course in the reefs.

I find the reactions to this voyage quite amusing. On the one hand are the
nay sayers who claim it is irresponsible to have let one so young go out on
the big ocean alone. On the other hand are the ones who say his parents are
exerting too much control and oversight. Where in the middle is the
microslice of appropriate parenting?

--
Roger Long