IR21 stands for International Roaming Information Document or International Roaming Technical Specification.
(IR21) is a document that contains information about the mobile network operator’s technical and commercial capabilities to provide roaming services to other operators. IR21 is used by operators to exchange and update their roaming information with each other, such as network coverage, supported technologies, tariffs, billing, quality of service, and security. IR21 helps operators to establish and maintain roaming agreements with each other, which are contracts that specify the terms and conditions for providing mobile services to customers who travel outside their home network’s coverage area. IR21 is standardized by the GSM Association, which is an industry organization that represents the interests of mobile network operators worldwide. IR21 can be submitted and accessed through the RAEX service, which is a service provided by the GSM Association to facilitate the exchange of roaming agreements between operators.