IMSI

International Mobile Subscriber Identity

This is a unique number that is associated with all GSM network mobile phone users.

An IMSI is fifteen digits long, the first three digits are the Country Code (MCC[?]), the next two are the network code (MNC[?]) and the remaining ten digits are the unique subscriber number within the network's customer base.

Example

210101234567890

210 - Germany 10 - Deutsche Telecom[?] 1234567890 - Subscriber ID