I have the habit of sometimes getting back on older threads because I feel strongly that an update might make a difference for someone having used the search function.

Here is my recap:

Cycling through the world you might cross areas where your cell phone won´t work due to lack of network coverage.
Should problems arise then, a connection to the world might be worth the extra money for a satellite phone.

Satellite phone services (in declining order by coverage) are offered by:

www.iridium.com
www.globalstar.com
www.thuraya.com


The global coverage differs VERY much.
For instance South America is not covered by Thuraya, Southern Africa is not covered by Globalstar.
As far as I know Iridium has the best coverage overall .

You can buy the phone (beware , sometimes even a simple charger is an extra) and sell it after your trip through an auction plattform
or rent the equipment.

The prices for one minute can be very reasonable (starting from around 50 ct $) if you take into consideration current roaming prices,
BUT you will also lose those minutes in some calling plans if you don´t use them up in a certain period of time.
The prices vary a lot, so it is imperative to compare!

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For German readers a few tidbits:

The German distributors are:

For Iridium
http://www.smartsatcom.com/german/index.php?option=com_frontpage&Itemid=1

For Thuraya:
www.thuraya.de

For Globalstar:
http://www.cpn.de/index.php?site=cpn_profil_de

Some distributors offer also renting their equipment, you might want to ask for their long term conditions.

Mail order resellers I know of:
www.woick.de
www.daerr.de

This should be it for a general overwiew

Take care,
moogley