MCC and MNC (Mobile Country Code, Mobile Network Code)
Updated
The MCC and the MNC are the two codes that identify a mobile network worldwide. The MCC has 3 digits and designates a country or an international area, for example 208 for France or 262 for Germany; the MNC has 2 or 3 digits and designates a network within it. They are assigned under ITU-T E.212.
In practice
MCC and MNC form the first digits of every IMSI and the network identity broadcast by every cell. MCC 901 is a shared code for networks that are not tied to one country, and some countries use these codes to spot SIMs in permanent roaming.