Mobile Country Codes (MCC) in combination with Mobile Network Code (MNC) is used in wireless telephone networks (GSM, CDMA, UMTS, etc.) in order to uniquely identify a mobile operator (carrier) using GSM, UMTS, LTE and sometimes CDMA mobile networks.
This MCC/MNC tuple is used then to identify the provider of a SIM card and is also used to identify the mobile network a device is connecting to in roaming scenarios. In the user interface it is utilized to identify the mobile operator for the last connection of each SIM and for each connection in the session reports.