Hi KIXMan,

For emergency voice comms, www.iridium.com is the best network. It's design is based on the idea that it can keep running if earth were wiped out. No ground-based facilities need to survive in order to make a call.

You can get a SIM with a couple of hundred minutes and a 1 year expiry for about 500.00 USD++.

Be advised that satellite communication is not designed for use in an urban environment. You need to have an unobstructed view of at least 80% of the sky to get optimal performance. Less than 50% and you probably can't connect at all.

If there were a civil war / earthquake / whatever and your normal terrestrial communications are down you would need to be on your hotel's roof to make a call / receive messages. Alternatively you would need a little antenna that has a magnetic / clip on base and set that up on your balcony. That would work if you are in an ocean resort and have a balcony. But thinking downtown Bangkok, you would really need to access the roof.