...
Almost all EAP types support the use of anonymous outer identities. The primary use of anonymous outer identities is for better preservation of privacy for your users; a properly configured supplicant will then not even reveal the real username of the user to the visited eduroam SP; instead, the username is replaced with a dummy value.
This feature needs protocol support by the EAP type in question; the basic idea is that there have to be two stages of communicating the client identity:
...