There are also other variants of the ARFCN numbering scheme that are in use for other systems that are not GSM. One such example is the TETRA system that has 25 kHz channel spacing and uses different base frequencies for numbering.
In addition to the GSM system, there are alternative variants of the ARFCN numbering scheme used in different communications technologies; one example is the TETRA system with 25 kHz channel spacing and distinct base frequencies for numbering.