Iridium has orbiting satellites. Here the proximity to the equator plays the decisive role, because at the equator the satellite density of the Iridium network is lowest. On the sea, however, this is negligible because there is a clear view all around, even to satellites located flat above the horizon.
Satellite communication in Cuba
Import and use of satellite based communication devices are restricted by the Cuban authorities.
If the immigration authorities find such equipment it will be confiscated, it requires considerable efforts to get it back when you leave Cuba. If and in which way these rules will be applied if you reach Cuba with a vessel with build in satellite devices is beyond our knowledge.
Despite any rules the devices are working, as we specially know for Iridium devices due feedback from our customers.
Information from March 2018: Visitors are required to obtain authorization to bring satellite phones into Cuba.