I would start my search here: Global Marine Networks
Look at their XGate email
product, the Iridium
satphone, and an external antenna
. You can buy Iridium
phones from many sources, but GMN is a good one. I personally use Outfitter Satellite
for my phone hardware
and airtime, but GMN is probably just as good, and is definitely a full-service outfit. I have been very happy with XGate.
I don't know about the tsunami warnings, but if you can find a source for the SMS warnings the Iridium phones can receive them.
As you have seen there are many available options and products, but I think if you look at the GMN (Iridium and XGate) you won't be disappointed.