Roaming Consortium Organisation Identifier

What is a Roaming Consortium Organisation Identifier (RCOI)?

RCOIs are used by the Passpoint specification published by the Wi-Fi Alliance (WFA) in charge of hardware certification to all latest Wi-Fi standards, and also by the OpenRoaming specification as published by the Wireless Broadband Alliance (WBA). 

Where are they registered?

RCOIs are not registered in a central registration authority per se, like RADIUS attributes might be (with the IANA), or a mobile network MCC/MNC pair (with the 3GPP). 

However, RCOIs as they currently exist are derived from a registration at the IEEE. The IEEE is in charge of assigning MAC addresses, amongst other things, and here, some organisations have registered themselves and used some of their registration 'name space' to create RCOIs.

Are there examples of such registrations?

Yes. 

Cisco owns the 00-40-96  block of MAC Addresses under the large MAC address block scheme, referred to as MA-L. The 00-40-96  RCOI used by Cisco's older legacy settings for OpenRoaming is quite obviously derived from that registration. 

GEANT on the other hand is registered under the MA-S block scheme as 00-1B-C5-04-6 (the 00-1B-C5 block in the MA-L registry is reserved for the IEEE, who chopped that block into small registrations). GEANT has assigned the sub-registration 00-1B-C5-04-60  to eduroam. 

The WBA does not have a registration under any of the MA blocks, but has a so-called Company ID. That Company ID is 5A-03-BA, and all current WBA RCOIs are derived from this registration. 

How do you get an RCOI?

The process is probably as simple as obtaining a Company ID or a registration in the MA-S block from the IEEE. The IEEE will have more information on its Registration Authority page here: https://standards.ieee.org/products-programs/regauth/