Sony Ericsson Z600
warning on z600
In the U.S. prior to 2002, GSM technology only operated in the PCS (1900 MHz) frequency band. AT&T is making heavy use of 850 for GSM.
GSM 850 addresses the needs of carriers with Cellular licenses switching from other technologies to GSM.
Before the existence of GSM 850, the Cellular band was commonly referred to as the "800 MHz" band. "850 MHz" implies a different frequency band, but this is not the case. "800 MHz" and "850 MHz" refer to the exact same frequency band. 850 is technically a more accurate description of the frequency range, but 800 is the original, and more common term.