Need advice on international "in case of emergency" cell phone

Hi all,

Need some advice.  We have a department with staff who work primarily offsite.  The department would like to provide some "in case of emergency" cell phones to them and have asked us to recommend both the best device and carrier.

These are the requirements-

-      They should be simple phones- no need for data (maybe a flip phone?)
-      They would need an international plans and a minimum monthly plan since these would only be used in case of emergency.
-      They would need to be quad-band. 850 Mhz, 900 MHz, 1800 MHz and 1900 MHz which would cover all countries, including Japan.

Any advice would be most appreciated!

Thanks!