Iridium works fine.
There's no such thing as a filed ATC flight plan for down low in that part of that part of the world.
There are comms operators who are holding SAR at whatever predetermined intervals are decided. There's also a met forecaster and/or observer on duty during flying ops keeping an eye on things. They are all on first name terms living together with the aircrew. The oversight and planning is excellent, everyone knows what's to be achieved and how it's being done.