An International Mobile Subscriber Identity (IMSI) is a unique number, usually 15 digits long, that identifies a user of a mobile network. The IMSI is usually available in the sim management system of the IoT connectivity. The exact format of the IMSI varies by mobile operator, but some things are always constant:

IMSI: the constant factors

  • The first 3 digits represent the Mobile Country Code (MCC).
  • The next 2-3 digits represent the mobile network code (MNC, the mobile operator).
  • The remaining 9-10 digits uniquely identify the subscriber within a particular mobile network. Some operators use the first two digits to indicate the home location register.