IMSI

Detailed Information:
The IMSI consists of the:

MCC (Mobile Country Code)
The MCC identifies the country.
MNC (Mobile Network Code)
The MNC identifies the PLMN within a country.
MSIN (Mobile Subscriber Identification Number)
The MSIN identifies the mobile subscriber within a PLMN. The allocation of the MSIN's is a matter of each network operator.

Note 1:
The IMSI shall not be longer than 60 bits (<=> 7.5 octets).

Note 2:
The IMSI is not the directory number (telephone number / MS-ISDN) of a mobile subscriber.