Mobile Country Number (MCC)

Defined
Mobile Country Code (MCC) consists of three-bit decimal numbers that indicate the country in which the mobile user (or system) belongs.
Format
Mobile Country Number (MCC) consists of three decimal digits with a coded range of 000-999 decimal
Transfer
The mobile country number is used in international Mobile user identification (IMSI) and in location area recognition (LAI).
Location Area identification (LAI). The location area identification is sent periodically in the system messages for each cell broadcast, where the mobile country number (MCC) indicates the country gsmplmn belongs to. Mobile station will receive this information as one of the important basis for network selection.
The IMSI of the mobile station. The mobile IMSI also contains the mobile country number (MCC), which represents the country in which the mobile user resides. When the mobile station logs on or applies for some kind of business on the network, the mobile station must report the IMSI to the network (in the case where Tmsi is not available). The network is based on the mobile country number (MCC) in IMSI to determine whether the user is an international roaming user.
Settings and impact
As the world's only national identification standard, MCC resources are distributed and managed uniformly by the ITU (ITU). ITU recommendation E. 212 (Blue Book) specifies the MCC numbers for each country. China's mobile country number is 460 (decimal). Because of the special meaning of MCC, it is not allowed to change once it is set in the network.