NAI
network access identifier
The NAI is used to address a user in a specific Internet domain. The format of an NAI is similar to that of an address. It is comprised of a user portion that identifies the individual node and a realm portion that identifies an administrative domain in the Internet. The two portions are separated by an @ sign. The ROAMOPS working group is in liaison with bodies such as the ITU and 3GPP in order to integrate NAI with variables such as the E.164 telephone number range and the IMSI.