NCC - Network Colour Code
The Network Colour Code is a part of the Base Station Identity Code (BSIC). This code is used in GSM to uniquely identify a base station within a particular geographic area. The NCC is the part of the BSIC that identifies the operator. The NCC is also called the Public Land Mobile Network (PLMN) colour code.
The BSIC is needed to identify a base station, because more than one base station can use the same frequency for their broadcast channel. This is especially the case in border areas, where operators at both sides of the border might use the same frequencies for their base station broadcasting channel.
The NCC is a 3 bit code (with a value of 0 up to 7).