Satellite phones are the way to go.
I work in the SW USA desert flying a lot of S.A.R. missions as a helicopter pilot for the US Gov't. Even while our a/c are equipped with an E.L.T. (Emergency Locator Transmitter), which would transmit on all the required emergency frequencies in the event of a crash with crew incapacitation, we still carry an Iridium Satellite telephone with us.
Sometimes you just need non-emergency help (run low on fuel, mechanical trouble, etc) but not an all-out expensive rescue effort. That's when the Sat phone comes in real handy. You can explain your exact problem to a human. The phones cover 100% of the earth.
You can rent those sat phones for about USD$40 / week. The calls are expensive at something like $5-6 per minute from landline to the Sat-phone, and about USD$3-4 for calls from the Sat-phone to a landline, but it's still cheap insurance.
Service is generally not available inside buildings, but this is a small inconvenience when you realize that you can use Iridium satellite phones anywhere, whether you're on the high seas, the Amazon jungle or at the South Pole. Having access to such an extensive global network will give you peace of mind as you venture out in your travels, the Iridium Phone a trusted lifeline to the world.
The voice quality can vary from excellent to very scratchy, depending on how many satellites it has to pass through.
They have an International SOS service also.
They have many other capabilities/services too numerous to mention here (Fax, SMS, Paging, etc.)
For more info go to:
http://www.iridium.com/service/iri_service-home.asp
(Of course, it goes with out saying that you should carry a GPS with you so you can give your exact location to the person you are calling.)
Ride safe...
[This message has been edited by gyuris (edited 18 November 2005).]