The Absolute Radio Frequency Channel Number (ARFCN) is a unique identifier assigned to each radio channel within the GSM network. It serves the purpose of determining the precise frequency of a given radio channel.
In the GSM900 band, ARFCN numbers range from 1 to 124. Meanwhile, in the GSM1800 band, ARFCN numbers span from 512 to 885. Notably, the ARFCNs used in GSM1900 partially overlap with those in GSM1800. For GSM1900, ARFCN numbers 512 to 810 are employed. In cases where a mobile phone operates across multiple bands, it will interpret ARFCN numbers 512 to 810 as frequencies either within the GSM1800 or GSM1900 bands. To make the correct interpretation, the mobile phone requires an additional parameter known as the BAND_INDICATOR.
A complete list of the ARFCNs and the associated radio channels is given in the table below.
| Band | Name | ARFCN | Uplink (MHz) | Downlink (MHz) |
| GSM400 | GSM450 | 259 ≤ n ≤ 293 | 450.6 + 0,2×(n-259) | fup(n) + 10 |
| GSM480 | 306 ≤ n ≤ 340 | 479.0 + 0,2×(n-306) | fup(n) + 10 | |
| GSM700 | GSM750 | 438 ≤ n ≤ 511 | 747.2 + 0.2×(n-438) | fup(n) + 30 |
| GSM850 | GSM850 | 128 ≤ n ≤ 251 | 824.2 + 0.2×(n-128) | fup(n) + 45 |
| GSM900 | Primary GSM | 1 ≤ n ≤ 124 | 890 + 0.2×n | fup(n) + 45 |
| Extended GSM | 0 ≤ n ≤ 124 975 ≤ n ≤ 1023 | 890 + 0.2×n 890 + 0.2×(n-1024) | fup(n) + 45 | |
| GSM Rail | 0 ≤ n ≤ 124 955 ≤ n ≤ 1023 | 890 + 0.2×n 890 + 0.2×(n-1024) | fup(n) + 45 | |
| GSM1800 | GSM1800 (DCS1800) | 512 ≤ n ≤ 885 | 1710.2 + 0.2×(n-512) | fup(n) + 95 |
| GSM1900 | GSM1900 (PCS1900) | 512 ≤ n ≤ 810 | 1850.2 + 0.2×(n-512) | fup(n) + 80 |