Hello,
there is a standard called EAP-SIM/AKA used for authorization against RADIUS. It employs SIM card as it contains credentials. It needs to be supported on both AP and RADIUS server itself, or at least - on AP only with RADIUS able to proxy the request to another RADIUS. This RADIUS / proxy validates credentials in 3GPP database.
Standard is already supported by many mobile vendors including all Nokia, iPhone, some Androids. More valid info about the standard gives Google.
As it pops out on every new modern devices, I would like to ask if and MikroTik / RouterOS will support it? I know it’s probably most interesting for WLAN / 3g operators, but hey, that is a huge market.
Thanks and best regards.