IMSI Validator (MCC/MNC)

What the IMSI is

The IMSI (International Mobile Subscriber Identity) identifies a subscriber on a cellular network. It is stored on the SIM card and has up to 15 digits, following the ITU-T E.212 standard. The IMSI is confidential — it is not your phone number, and modern networks mask it to prevent tracking. The dialable number is the MSISDN.

How the IMSI is structured

• MCC — Mobile Country Code, 3 digits (e.g. 724 = Brazil).
• MNC — Mobile Network Code, 2 or 3 digits, identifying the operator.
• MSIN — Mobile Subscriber Identification Number, up to ~10 digits, assigned by the operator.

Together, MCC + MNC form the PLMN identifier (Public Land Mobile Network), which uniquely identifies an operator in a given country.

How it is validated

There is no checksum in an IMSI. Validation is purely structural: the total length (14–15 digits), a plausible MCC, and an MNC of the right length for that country. A structurally valid IMSI is not necessarily assigned to a real subscriber.

Common pitfalls

• Expecting a check digit — unlike IMEI or ICCID, the IMSI has none.
• Assuming the MNC is always 2 digits — some countries use 3-digit MNCs.
• Mistaking the IMSI for the phone number (MSISDN) or for the device IMEI.

FAQ

Is the IMSI my phone number? No. The dialable number is the MSISDN. The IMSI is a private subscriber identity stored on the SIM.

How long is an IMSI? Up to 15 digits: 3 for the MCC, 2 or 3 for the MNC, and the rest for the MSIN.

Does the IMSI have a check digit? No. Validation is structural only — there is no Luhn or similar checksum.