★ Absolute Radio Frequency Channel Number, a code to specify a pair of physical radio carriers and channels within the spectrum that is allocated for cellular mobile communications.

★ ARFCN is used for transmitting and receiving on the UM Interface, one to uplink signal and one to downlink signal.

★ ARFCN's bandwidth is 270.833 kHz; channel spacing is 200 kHz in a given GSM band.

★ The uplink-downlink spacing is generally 45 / 50 MHz.

★ If Frequency Division Duplex is operated in the system, then the channel number is associated with both uplink and downlink radio channels.

★ ARFCN is 1-124 within GSM900 spectrum, 512-885 within GSM1800, 512-810 within GSM1900, are used.