IFPI is the International ISRC Agency. Authoritative information on the global ISRC system can be found here.
Other National ISRC Agencies
You can access a complete list of other National ISRC Agencies here.
ISO Technical Committee 46, Subcommittee 9
ISO/TC 46/SC 9 is responsible for developing and maintaining the ISRC standard, known as ISO 3901, Information and documentation -- International Standard Recording Code (ISRC)
Sound Exchange is a non-profit collecting society/performance rights organization that specializes in digital performances.