I know one guy who has it but doesn't like it. His experience with their customer service has been bad and the service he gets isn't great. I haven't ever talked to a single tech (third party types with no affiliations) that liked dealing with them. IP communication was never meant to go into space, so there's some funky stuff that has to be done to make it work even half way decent. I had to run similar services in the Army and I have a slight bias against it because I've seen that type of technology suck first hand
Also, they have a division that competes directly with the company I work for. That's really neither here nor there, it's just the selfish reason.