Personal Communications Service or 
PCS is the name for the 1900 
MHz radio band used for 
digital mobile phone services in the 
United States.  
CDMA, 
GSM, 
iDEN, and 
TDMA systems can all be used on PCS frequencies. The 
FCC set aside the band of 1850-1990 MHz for mobile phone use in 
1994, as the original cellular phone band at 824-849 MHz was becoming overcrowded. Newer "dual-band" phones are capable of working in both the 800 and 1900 MHz bands.  However, they are incompatible with European systems, which use 900 and 1800 MHz.
External link: FCC: Broadband PCS (http://wireless.fcc.gov/services/broadbandpcs/)
 
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