Welcome to the International Mobile Subscriber Identity (IMSI) Home Page. IMSIs were created and formatted to provide the unique international identification of mobile terminals and mobile users and to enable those terminals and users to roam among public networks which offer public mobility services.

The IMSI Assignment Guidelines and Procedures are maintained by the IMSI Oversight Council (IOC).

Telcordia Technologies is responsible for administering the assignment and use of IMSIs in the United States and other North American Numbering Plan (NANP) countries.

Telcordia Technologies, as IMSI Administrator, participates in the management of all segments of the IMSI, but directly administers only the Home Network Identity (HNI) segment. HNIs are assignable to operators of public mobility services with international roaming capabilities. The HNI uniquely identifies the home network of a public mobility service subscriber and contains the Mobile Country Code (MCC) and the Mobile Network Code (MNC). The remaining segment of the IMSI, the Mobile Station Identification Number (MSIN), is directly administered by the network operator to which the HNI is assigned.

For questions regarding IMSI assignment, please email Connie Hartman at chartman@telcordia.com, or by calling 732-699-4204.