You can actually achieve this even with Iridium Go. I tried it years ago and it worked.

It isn't too documented, or let me say it isn't documented at all but you can write AT commands and start raw TCP connections and read and write to that socket.

And it is actually reasonably priced. I tried to open SSH connections and it was barely usable. You get a very small number of bits per second.

Edit: Found the private repo I had created back then in case anyone has any interest. It looks like I did something like this:

    func (sess *IridiumGoSession) ActivateDataWithCustomSettings() (*PerformTaskResponse, error) {
     return sess.PerformTask("2",
      MakeOption("set state", "true", "bool"),
      MakeOption("Firewall allow all traffic", "false", "bool"),
      MakeOption("Firewall exceptions", "XXX.XXX.XXX.XXX-all-tcp", "bool"),
      MakeOption("Enable DNS forwarding", "false", "bool"),
      MakeOption("Dial number", "0088160000330", "bool"),
     )
    }

Need to replace `XXX.XXX.XXX.XXX` with the IP you want to establish a connection to. And I don't know where I got 0088160000330 from. I guess that's the internet call number.