The RockBLOCK is even compatible with Raspberry Pi! https://www.rock7mobile.com/products-rockblock
Nice to see that the iridium fiasco has resulted in some long tail utility
edit: here's a page with a proof of concept with an arduino hookup: http://makezine.com/projects/make-37/iridiumsatellite/
I think it'd be cheaper to build your own acoustic modem and glue it to a handset.