A method is provided that includes obtaining an access request for a device to access a visited access network, the access request including an authentication identifier for the device including an identity for the device and a realm comprising a network identifying portion; determining a re-write rule for the realm by querying a database based on an identity type of the device and the network identifying portion of the realm, the database including a plurality of re-write rules for a plurality of networks and a plurality of identity types; re-writing the realm based on the re-write rule using the identity for the device to generate a re-written realm; obtaining, based on the re-written realm, an address for an authentication server of an identity provider associated with the device; and performing an authentication with the authentication server using the authentication identifier to authenticate the device for the visited access network.