From what I understand, those are a lower level of service (i.e. no voice) that are basically a global inReach that benefit from the worldwide coverage. Same general concept as the Garmin though so not really necessary unless you find yourself venturing outside Garmin's coverage.
The Iridium GO 9560 portable satellite phone with wifi is iridiums newest satphone with global coverage and functions with smartdevices. Call for more..
www.northernaxcess.com
I have the InReach as well and provides a sense of security when going solo. Have wanted to get a sat phone so could more easily check email. Definitely will look into this. Thanks
That link gives a good description, basically serves to merge your cellular device to satellite, so phone, internet sms, GPS, etc.
I would rather use a bridge device than a stand alone device, the Iridium allows up to 5 connected devices at a time.