GSM (Global System for Mobile Communications) is a 2G mobile phone technology. In common usage, "GSM" encompasses its data counterpart, GPRS, and their successor 3G standards, EDGE (also known as IMT or EGPRS) and UMTS.
I currently have a Nokia 1200 and I've never visited an area where it doesn't work.
My phone operates on 900/1800 MHz, so it will not work in the USA.
Soon, I will visit the USA for approximately one ...