The purpose of the GUTI is to provide an unambiguous identification of the UE that does not reveal the UE or the user's permanent identity in the EPS. It also allows the identification of the MME and network. It
can be used by the network and the UE to establish the UE's identity during signalling between them in the EPS.
The GUTI has two main components:
the GUMMEI that uniquely identifies the MME which allocated the GUTI; and
the M-TMSI that uniquely identifies the UE within the MME that allocated the GUTI.