Hi Fridayman
That $300 rip off must be a new thing from Telstra. I did exactly the same thing about 3-4 years ago and it only cost me the $10.
It pays to fire up the sat phone and test the sim still works every month or 2 (if your not a regular user). Once when I tried it, it didn't work. I had to ring Telstra and get it put back on. When I asked why it didn't work, they dodged and ducked and weaved and wouldn't answer the question. The Asian sounding girl I dealt with even tried to hide behind the old "don't understand the question" trick.
It wouldn't be good to be out bush and need it in an emergency and it didn't work. The problem WAS a Telstra problem with the card, nothing wrong with the phone or the sat system.
Cheers
JGM