This is an old revision of the document!
http://wiki.groundlab.cc/doku.php?id=gsm_library
Modules
M590
http://www.14core.com/wiring-the-neoway-industrial-type-m590-m590e-gsmgprs-sms-notification/
http://arduinotehniq.blogspot.de/2015/09/gprs-module-with-m590-for-sms-projects-1.html