Section: 5.4.3.3 Identification response by the UE
Content: A UE shall be ready to respond to an IDENTITY REQUEST message at any time whilst in 5GMM-CONNECTED mode. Upon receipt of the IDENTITY REQUEST message: a) if the Identity type IE in the IDENTITY REQUEST message is not set to "SUCI", the UE shall send an IDENTITY RESPONSE message to the network. The IDENTITY RESPONSE message shall contain the identification parameters as requested by the network; and b) if the Identity type IE in the IDENTITY REQUEST message is set to "SUCI", the UE shall: 1) if timer T3519 is not running, generate a fresh SUCI as specified in 3GPP TS 33.501[ Security architecture and procedures for 5G System ]  [24], send an IDENTITY RESPONSE message with the SUCI, start timer T3519 and store the value of the SUCI sent in the IDENTITY RESPONSE message; and 2) if timer T3519 is running, send an IDENTITY RESPONSE message with the stored SUCI.