Section: 28.7.4 Emergency NAI for Limited Service State
Content: This clause describes the format of the UE identification when UE is performing an emergency registration and IMSI is not available or not authenticated. The Emergency NAI for Limited Service State shall take the form of an NAI, and shall have the form username@realm as specified in clause 2.2 of IETF RFC 7542 [126]. The exact format shall be: imei<IMEI>@sos.invalid NOTE: The top level domain ".invalid" is a reserved top level domain, as specified in IETF RFC 2606 [64], and is used here due to the fact that this NAI never needs to be resolved for routing. or if IMEI is not available, mac<MAC>@sos.invalid For example, if the IMEI is 219551288888888, the Emergency NAI for Limited Service State then takes the form of imei219551288888888@sos.invalid. For example, if the MAC address is 44-45-53-54-00-AB, the Emergency NAI for Limited Service State then takes the form of mac4445535400AB@sos.invalid, where the MAC address is represented in hexadecimal format without separators.