https://www.inmarsat.com/en/solutions-services/maritime/serv...
Or Globalstar.
https://www.globalstar.com/en-us/blog/articles/satellite-sol...
there is zero globalstar mid ocean coverage.
there is a reason you will see lots of competing options for people integrating the iridium embedded modems into things designed to go on top of $40 million business jets and just about zero globalstar.
It was for his Spidertracks[1] flight tracking system. (Which, with the ADSB track, helped us hone in on the possible location. The wreck ended up being right in line with the last few pings.
[0] https://lompocrecord.com/news/local/experienced-solvang-bush...
I'd expect most of them to go with one of the Ka band these days; they have pretty small antennas available these days as far as I know.