I've used both Iridium and KVH VSAT phones. Iridium is low-earth orbit satellites, while the VSAT uses satellites in fixed orbits.
Iridium works well IF you use an external antenna. In my experience, voice quality is OK. Data is slow (if I remember, 9600 baud). You're charged by the minute of usage (data is cheaper than voice). Our experience was that a call would frequently be dropped when the phone had to switch satellites -- which happens quite frequently (those satellites zip by very quickly). In SE Alaska, high fjord walls sometimes made it hard to get a signal. Iridium is relatively inexpensive, as satellite phones go (equipment was $1K or so, plus another $1K for a fixed base station and antenna). Voice ranges from $1 / min to $2 /min, prepaid. Prepaid minutes expire after a time period (depends on the plan you buy). One nice thing about Iridium is it works world-wide. Iridium went bankrupt soon after they launched the initial constellation of satellites, but the service was considered so critical that they were resurrected and have successful maintained the constellation and service over quite a time period.
KVH VSAT is a dream to use. Voice quality is as good or better than cell phones. Data is fast (how fast depends on equipment and plan). Coastal coverage for North America is pretty good (not sure about SE Alaska, check the KVH coverage map). Coverage on the high seas is less complete. The equipment uses gyro-synchronized movable antenna dishes, and is quite pricey ($10K-$20K, if I remember correctly). The antenna is amazingly small. The electronics are bulky and power hogs.
Another choice is Globalstar, I think. They went belly-up a number of years ago when their satellite voice transponders got old and failed. But their data transponders still worked, so they invented SPOT, which is very popular (and inexpensive). They've put new satellites up and have voice once again. I don't have any experience with them.
Jeff
