In May 2018, IOC expanded its support for the management of IMSI codes by developing and approving guidelines that support the assignment of IMSIs for the Citizens Broadband Radio Service (CBRS) shared spectrum users in the 3.5 GHz band. This effort was done in collaboration with the CBRS Alliance.
IOC is an open industry council of telecommunications companies and other organizations with a direct interest in the management of IMSI codes — the critical 15-digit number used within mobile phones that allows service operators to identify mobile terminals for purposes of international roaming — as well as the Shared HNI code and IMSI Block Number (IBN) for CBRS spectrum users. The IOC oversees the management of IMSI codes that have been assigned to the United States and its possessions as authorized by the U.S. Department of State since 1996.