Regular Operation as per DS			GSM SPEC

GSM900 Tx: 870.4 ... 921.4 MHz			880.0 ... 914.8	
GSM900 Rx: 864.4 ... 966.2 MHz			925.0 ... 959.8

GSM1800 Tx: 1702.4 ... 1919.8 MHz		1710.2 ... 1784.8
GSM1800 Rx: 1804.8 ... 1996.4 MHz		1805.2 ... 1879.8