A friend borrowed my Iridium phone and had to use their emergency services (911) - the call center that they were hooked up to was in his words "frighteningly competent." ...
Rambling Iridium thoughts:
I've enjoyed the service myself - with the phone and and a Psion Revo (It has a native serial port), I can telnet to any of my severs while in the woods. Strangely, it let's me relax knowing that I can help out my users.
At around 2400 baud - don't use SSH. Oh... Screen is your friend as it does cut out enough.
If you use a PC - it come with some proxy software and a proxy server that will remove/compress images, but any computer with a serial port can use it as a modem. Sadly, modern pdas lack serial ports, but old Posion Revos/5-series are cheap, last a long time, and have awesome keyboards and work well.
I have an older Motorola Iridium phone, so I don't know if this setup would work with the more modern phones.