The UE initiates the Attach procedure by the transmission, to the eNodeB, of an Attach Request. Following parameters are included in this message.

IMSI or old GUTI, last visited TAI (if available), UE Core Network Capability, UE Specific DRX parameters, Attach Type, ESM message container (Request Type, PDN Type, Protocol Configuration Options, Ciphered Options Transfer Flag), KSIASME, NAS sequence number, NAS-MAC, additional GUTI, P-TMSI signature, Voice domain preference and UE's usage setting) message together with RRC parameters indicating the Selected Network and the old GUMMEI.