Are you being obtuse? If you want to be on the Iridium network it's going to cost about $1k for a phone and $1 per minute to make a phone call. That's why it doesn't work, because it's just too expensive.
SAS is going to have significantly lower overheads because they don't offer what Iridium does, it's basic and it's cheap.
Shut your gob about Iridium, we heard you, it's noted.