Section: 4.7.3.1.2 GMM common procedure initiation
Content: If the network receives an ATTACH REQUEST message containing the P-TMSI type IE and the Mobile identity IE with type of identity indicating "TMSI/P-TMSI/M-TMSI", and the network does not follow the use of the most significant bit of the LAC as specified in 3GPP TS 23.003[ Numbering, addressing and identification ]  [10] subclause 2.8.2.2.2, the network shall use the P-TMSI type IE to determine whether the mobile identity included in the Mobile identity IE is a native P-TMSI or a mapped P-TMSI. The network may initiate GMM common procedures, e.g. the GMM identification and GMM authentication and ciphering procedure, depending on the received information such as IMSI, CKSN, old RAI, P-TMSI and P-TMSI signature.